So I recently received PCBs from jlcpcb.com. It cost me about $8 including delivery. Pretty cheap I think.

PCBs looked good so I started assembling one right away.

Once assembled I've checked mains part - works fine. First firmware for attiny is to blink the load. Works fine!

Next step: preparing firmware for tiny and esp. I'm planning to use communication protocol compatible with one from Sonoff dual.