This is about the third version now of our laser tag system for Tech Camp. Every time we've built a batch with kids we've made it simpler. This time we decided that we needed just one main PCB; it now has the batteries, sensors, microcontroller, LED display bank and associate circuitry on it.

We've tested a batch out with kids and it's now possible for even those younger children who are new to soldering to be able to construct it all in a single day session. The main body is made of 4 layers; the two inside ones are 3mm MDF, and the two outside ones are a silver-coloured laser engraveable laminate. We've used the same optics setup as last time, but Jack was keen to increase the robustness by inserting two stiffening supports through which the black tube passes, which then slot into the main body. It is still secured with two cable ties and the combination of all this means that the optics are naturally pretty well aligned with the sights of the gun. Another minor change that has made them easier to construct is having the IR emitter PCB circular; this fits snugly in the pipe/connector system and doesn't require a separate mounting board.

It's turning out to be quite a sophisticated system now. Using a version of the same PCB set up as a 'control box', we can put the laser taggers into many different modes to play capture the flag, escort the VIP, and a version of 'domination' (where the winning team is the one who has control of the box for the longest throughout a fixed-time game). We can even download the scores to a PC using an IR USB dongle.

This picture is one of a bank of 20 that we've produced to take to parties and events. (Many thanks to Jack, Felix, Harry and Jenny for helping out with these!) The version that the kids will be producing this summer will be almost identical but be completely made of MDF so they can choose their own colour scheme.