I was at a point of zero stock for my useless machines with half a dozen back orders. It seemed to be the perfect time to upgrade the internals (A few of these had gone out before on workshops and other restricted events). This design uses marginally less wood but it also allows me to fit in a PCB under the switch. The PCB is a bit redundant when the circuit is so simple but it really does help when you're trying to get 10 kids finished in 2 hours (I've not succeeded yet).
This kit can be purchased through my shop here