Should have used a through-hole design. No instructions.
For "Should have used a 555"
This is a kit and the description on Tindie states one should go to the seller's website for assembly instructions. In fact, there are no assembly instructions there. I have a fair amount of electronics knowledge and experience, so was able to assemble it without instructions. Most of the components are surface-mount which makes hand-assembly tedious. You need good magnification, a steady hand, a PCB holder, a solder station with a fine-tip iron and hair-thin solder. Alternately, you can use paste solder and an oven. The surface-mount switch broke after just a few operations. I replaced it with a much more robust through-hole switch. It's all a shame. There is plenty of room on the PCB to have used a through-hole or socketed parts design, which would have made assembly much faster and resulted in a tougher product.
Unless you understand electronics pretty well and have experience with surface-mount soldering, don't buy it.