Electric playdough infinity mirror

A soft play we go to has several infinity mirrors which look like they are really deep with row after row of LEDs. When he was a baby, the toddler was fascinated by them. I thought we could try and make one as a fun thing to do with our electric play dough.

I ordered a piece of clear perspex and some stick on partially transparent mirror film. The film is the sort of stuff that you put on windows for privacy and you can get small sample size pieces quite cheaply. You have to use a mix of water and detergent to clean the surface of the perspex and stick on the film, and a squeegee to smooth it. I'm not sure if it was the small size that made it fiddly (it was 9cm square, the size chosen because of the sample size of the film) but I wouldn't fancy putting it on a window; I got a couple of little air bubbles in that I just couldn't remove, but overall it made a pretty decent mirror. The idea is that it reflects most of the light (apparently 80% for the film I bought) and the other 20% passes through.

The other thing I needed was a 'normal' mirror. I made one by sticking sticky-backed mirror on some plastic from our recycling box and made it the same size as the other mirror (9x9cm). Next, we put play dough and LEDs around the edge of the 'normal' mirror. We knew that 4 LEDs in series would only light dimly which wasn't what we wanted. We therefore put an LED on each side of the square and connected them with play dough such that two LEDs were in series in each branch of a parallel circuit (see diagram below).

Our first infinity mirror

Circuit diagram for our infinity mirror

We checked that the LEDs lit, and had a look at their reflections in the mirror - it looked like we had two of each LED. We then put the partially transparent mirror on top, sandwiching the play dough and LEDs between the mirrors. We went into a darker room and took a look at our infinity mirror. The small boy quite liked it, but due to the less than perfect reflection of the mirror film, you could only see around 6 reflections before the image was too distorted. 

We had a play with another arrangement of LEDs, changing the colours around and adding a fifth LED just because we had 5.  The small boy was pleased with his creation!

I thought we could improve on the bottom mirror and ordered a 9x9 cm perspex mirror to try another day; this would both give a better reflection and give a bit more rigidity to the bottom layer to make it easier to pick up and look at.

A few days later, we went to the soft play for the first time in months as my baby is now old enough to enjoy it too.  The big one was too busy rampaging around to take much notice of the infinity mirrors, but his baby brother was keen to walk towards them repeatedly and gaze into them.

The little one and his favourite infinity mirror at the soft play

Later in the day, I made a new infinity mirror from the electric play dough and the new mirror as the big one was quite lethargic (too much running and climbing earlier!) and I wanted to spark his interest in something other than whining about everything! It worked far better than the original one we made, and he was keen to look at it in the dark.  His baby brother was keen to gaze into it too, although he also wanted to eat it and was a little upset that he was prevented from holding it!  The big one wanted to take it apart which he did quite carefully, and the baby looked very confused when his brother separated the mirrors and pulled out the play dough! The big one then had a play with the mirrors, finding that he could see his hand through one but not the other.

I briefly mentioned that we could see lots of reflections of the LEDs because the light bounces lots of times between the two mirrors, but he wasn't in the mood for explanation so we didn't discuss it any further.

Improved infinity mirror - the photo doesn't quite do it justice but it was better than the first one.

The infinity mirror in daylight (looks a lot less exciting)

I think we will come back to the mirrors another time and maybe build an infinity mirror with more LEDs when I confess to the boy that I have more than 5 in the cupboard. The baby is keen on all types of mirrors so I plan to think of some more activities with mirrors and light where they can both play together (without LEDs that can be eaten).