Lasercut ply and cardboard, bicycle inner tube.
Here are my DXF files for the parts.
The three lasercut layers are glued together, with bits of cocktail stick in the holes for alignment.
I used 6mm ply, it would probably work fine in acrylic.
Rounding the sharp edges on the slot for the card makes it a lot easier to insert the card.
If your harmonica has a different size or different hole spacing to mine, you may need to tweak the design to fit.
It's important that the card is a good fit in the slot, otherwise too much air gets out and the thing is very hard to blow. You can line the slot with tape to reduce the clearance. Try to get a snug but sliding fit.
It's tempting to make long slots or big holes in the card, but that lets air escape out of the top of the slot. Lots of smaller holes (5mm or so) works better.Home | Artefacts| Robots