3D Printing Microphone and Loudspeaker Holders for the Interferometer

How small laboratory improvements can make a big difference to teaching and learning

In education, research and development does not always mean producing something dramatic or futuristic. Quite often it begins with a simple frustration: a piece of apparatus does not quite do the job well enough.

That is often how some of the most useful ideas begin.

In our laboratory, we regularly build, adapt and improve equipment so that it works better for teaching. Sometimes standard apparatus is perfectly adequate. At other times, it is not quite right for the experiment, not robust enough for repeated use, or not easy enough for students to set up with confidence. That is especially true when working with wave experiments, where positioning and alignment can make all the difference between a clear result and a confusing one.

Our interferometer is a good example. It is a piece of apparatus that can produce excellent demonstrations and investigations, but only if the microphone and loudspeaker are held in exactly the right place. That sounds simple enough until you start using it repeatedly with students. A few millimetres out of line, a slight tilt, or an awkward mounting method can turn a beautiful experiment into a fiddly and frustrating one.

So the solution was obvious: design and 3D print dedicated holders for the microphone and loudspeaker.

It is a small R&D project, but one with real value. Better apparatus leads to better experiments, and better experiments lead to better understanding.

Why alignment matters so much in wave experiments

Wave experiments are wonderfully visual in theory, but in practice they can be surprisingly delicate.

When students investigate interference, they are trying to observe patterns that depend on very small differences in path length. In an interferometer setup, the loudspeaker must produce the wave consistently, and the microphone must detect changes in sound intensity accurately as it is moved through the pattern. If either component is not positioned properly, the readings become less reliable and the whole experiment becomes harder to interpret.

This matters because students are already juggling a lot of new ideas at once. They may be trying to understand:

constructive and destructive interference
path difference
wavelength
nodes and antinodes
why some positions give a loud signal and others a weak one

If the equipment itself is unstable or awkward, students can end up blaming themselves for results that are actually caused by poor apparatus setup.

That is one of the most important lessons I have learned over the years in teaching practical science: when students struggle, it is not always because the concept is too hard. Sometimes the equipment simply needs to be improved.

A microphone that droops slightly, a loudspeaker that is not pointing where it should, or a holder that slips during use can all make the experiment appear much more mysterious than it really is.

Good alignment removes unnecessary confusion. It allows the science to stand out clearly.

Starting with the real problem

This project did not begin with a 3D printer. It began with observation.

When using the interferometer, it became clear that there were several recurring issues:

the microphone needed to be held securely and consistently
the loudspeaker needed a reliable mounting position
components needed to remain aligned during repeated demonstrations
the setup needed to be easy for students to assemble and understand
the apparatus needed to be durable enough for repeated classroom use

In many school laboratories, the temptation is to improvise with clamps, tape, Blu Tack, elastic bands or whatever happens to be nearby. I have done all of those things over the years, and sometimes they work well enough for a one-off demonstration. But “well enough” is not the same as “good”.

Improvised setups are often:

less repeatable
slower to assemble
harder for students to copy
more likely to shift mid-experiment
less professional in appearance

When you are teaching, those little inefficiencies add up. If it takes too long to set up, or if the apparatus behaves unpredictably, valuable lesson time disappears.

So rather than accepting a slightly awkward arrangement, I decided to design something purpose-built.

Designing the holders in CAD

This is where 3D printing becomes so useful in an educational R&D setting.

Once you can design simple parts in CAD, you are no longer limited to what a supplier happens to sell. You can design exactly what you need.

For the microphone and loudspeaker holders, the design process involved thinking carefully about several practical questions:

1. How should the component be held?

The holder needs to grip the microphone or loudspeaker securely without damaging it. Too tight, and it becomes difficult to insert or remove. Too loose, and the component wobbles or slips.

2. How will it attach to the interferometer?

It is no good having a well-designed holder if it does not fit sensibly onto the rest of the apparatus. The mounting point must be stable and easy to use.

3. Does the design keep the component properly aligned?

This is the critical issue. The whole point of the project is to ensure consistent positioning. The holder must not only support the component but also guide it into the correct orientation.

4. Is it easy for students to use?

That is always an important design criterion in educational equipment. A design can be technically clever and still be poor for teaching if students find it confusing.

5. Can it be modified easily?

First designs are rarely perfect. It helps to create something that can be adjusted and improved after testing.

In practical terms, this meant taking measurements, sketching ideas, building a CAD model, and thinking through tolerances. A microphone body or speaker casing may not be exactly the nominal size, and 3D printed parts often need a little clearance to fit properly.

This is one of the satisfying things about CAD design. It is problem solving in three dimensions. You are not just drawing an object; you are thinking through how it will behave in the real world.

Printing, testing and improving the design

One of the great strengths of 3D printing is that it allows rapid prototyping.

In the past, making a custom holder might have required woodwork, metalwork, or a great deal of improvisation. Now it is possible to produce a prototype, test it, identify its weaknesses, and print a revised version quite quickly.

That is exactly what happened here.

The first print is rarely the final answer. In fact, I would almost worry if it were, because that would suggest the design process had not been ambitious enough.

With the microphone and loudspeaker holders, testing involved questions such as:

Does the component fit properly?
Is the holder rigid enough?
Does it keep the microphone or speaker at the correct angle?
Is it stable during use?
Can students insert and remove the component easily?
Does the design interfere with any other part of the apparatus?

Sometimes a design looks fine on the screen but reveals its flaws immediately once printed. A wall may be too thin. A clip may be too tight. A mounting slot may need slightly more clearance. A part may flex more than expected.

This is not failure. This is the design process working properly.

In fact, this iterative cycle is one of the most educationally valuable aspects of projects like this. It demonstrates real R&D thinking:

identify a problem
propose a solution
build a prototype
test it
evaluate it
improve it

That is exactly the kind of mindset we want students to develop.

Why better apparatus improves student understanding

It is easy to underestimate the educational value of apparently small equipment improvements.

Students do not learn practical science just by hearing explanations. They learn by seeing, handling, measuring and interpreting. If an experiment works clearly, they have a much better chance of connecting the theory to the reality.

A better holder for a microphone or loudspeaker may sound like a modest improvement, but its effect can be significant.

Clearer results

If the apparatus remains aligned, the interference pattern is easier to detect and more consistent from one run to the next.

Greater repeatability

Students can repeat the practical with a higher chance of obtaining similar results, which builds confidence and reinforces good experimental method.

Less distraction

If the equipment is fiddly, students focus on the difficulty of using it rather than the science behind it. Better apparatus removes that distraction.

Better demonstrations

A teacher demonstration becomes more effective when the apparatus behaves predictably and presents the phenomenon clearly.

More independent student work

If the setup is easy to use, students need less intervention and can spend more time thinking scientifically.

This is a point I feel strongly about. Good apparatus design is not a luxury. It is part of good teaching.

Turning a difficult practical into a clearer demonstration

Some practicals have a reputation for being “difficult”. Sometimes that reputation is deserved. More often, though, the difficulty lies not in the principle but in the setup.

Wave interference can easily fall into that category.

Students may understand the idea of waves overlapping on paper, but when they try to see or measure it in the laboratory, the result can seem vague or unreliable. If the apparatus is not well designed, the practical becomes one more example of science appearing harder than it needs to be.

That is why projects like this matter.

A well-designed holder can help transform the experience from:

“I’m not sure what I’m meant to be seeing”
to
“Ah, now I can see how the pattern changes”

That moment of clarity is what practical science should deliver.

The best demonstrations do not just prove that a theory is true. They help students feel that they understand why it is true.

A personal reflection on laboratory R&D

One of the things I enjoy most about running my own laboratory is that I do not have to accept equipment limitations as fixed.

If something does not work as well as it should, I can redesign it, rebuild it or improve it.

That freedom is enormously valuable. It means that practical teaching can evolve rather than remain stuck with whatever came in a catalogue years ago. It also makes the laboratory feel like a genuinely creative space. Teaching, engineering, design and experimentation all come together.

Sometimes that means building major pieces of apparatus from scratch. At other times, it means solving a much smaller but still important problem, like how to hold a microphone in exactly the right place.

There is also something satisfying about knowing that the finished part has a direct purpose. This is not 3D printing for the sake of it. It is not about printing gimmicks or decorative objects. It is about making the lab work better.

I think students benefit from seeing that as well. They see that science equipment is not magic. It is designed, made, improved and refined by people. That is a powerful lesson in itself.

The wider value of 3D printing in the laboratory

This project is only one example of what 3D printing can offer in education.

Once you start using it seriously, you realise how many opportunities there are. In a laboratory setting, 3D printing can be used to create:

custom holders and mounts
sensor brackets
spacers and guides
replacement knobs and clips
demonstration models
experimental fixtures
storage organisers
prototype science apparatus

It allows a laboratory to become more adaptable and more inventive.

For a teaching business like Philip M Russell Ltd, that matters enormously. Every improvement to apparatus supports the wider goal: helping students learn more effectively.

When the equipment works well, the lesson works better. When the lesson works better, students gain confidence. And when students gain confidence, they are more willing to engage with ideas that once seemed difficult.

That is a very worthwhile outcome from a humble 3D printed part.

Conclusion: small ideas, real impact

Designing and 3D printing microphone and loudspeaker holders for the interferometer may not sound like a grand innovation, but it represents exactly the kind of practical R&D that makes a real difference.

It begins with noticing a problem.
It continues with design, testing and improvement.
And it ends with better apparatus, clearer experiments and stronger student understanding.

That is what good laboratory development should do.

In teaching, the little things matter. A better holder can mean better alignment. Better alignment can mean clearer results. Clearer results can mean a student finally understands interference rather than simply memorising it.

That is a chain of improvement well worth pursuing.

And perhaps that is the real lesson here: innovation in education does not always arrive in dramatic form. Sometimes it is printed layer by layer on a 3D printer, fitted onto a piece of apparatus, and quietly makes the science easier to see.

Monday, 15 June 2026