Handheld mirror: Plan A

So, here's the first proper test mirror I intend to make.  The plan:

- First surface mirror
- 3D printed PLA plastic substrate
- Off-axis mirror
- approximately 20cm x 20cm

Details inside

Material test: aluminized mylar

I'm going to try some small scale mock-ups of paraboloid mirrors over the next few weeks.  First up: aluminized mylar, a thin plastic sheet with an aluminum coating.

I knew that there were some pretty serious disadvantages to using this material, and those turned out to be even more serious than I'd thought.  The only real advantage is cost.  I was able to make my handheld concave mirror for less than $5, and this video by Dan Rojas demonstrates that it's possible to build a concave mirror more than a meter in diameter for less than $25. His method involves stretching the mylar across a frame then applying suction to make it concave.

Caution: do not try this at home.  Fire hazard, blinding hazard.  This isn't just boilerplate. The blinding hazard turned out to be quite a bit worse than I'd expected, and I had thought I was already being a bit paranoid.  I would strongly recommend against copying the techniques I've used here; what I was doing was quick and crude, intended only to get a sense of how the material behaves.