Tiny wearable with stm32f401

I home etch using laser jet toner on glossy magazine paper. Laminating is easier since the board itself is much thinner. I'll be putting up a how-to, but it is the same as etching FR4.

I have been working mostly with a 1960s material called Electroply (it was the only flexPCB available on ebay at the time). It is much thicker and robust than Kapton copper clad. Both have good uses for wearables. I have been trying to get a real source for something like a PET based flexible copper clad as that should be similar to the Electroply. If we do a kickstarter, I will budget for a kit which includes a large sheet of Kapton at least. It is expensive stuff and it is great Adafruit is selling it (ebay is still cheapest usually). Dupont only sells it in big rolls. Another alternative is silver deposition - http://www.cartesianco.com/product/the-argentum/ .

We are also using low temp solder paste - http://www.chipquik.com/store/prod_smdltfp.htm to attach the modules.