To design this PCB I used the same EasyEDA site.

I had a two layer PCB, and one of these layers is almost completely occupied by a battery holder. So I used SMD switches with four pads, which were connected in two pairs. I used these internal connections to add  a virtual bridges over the PCB surface to pass wires across. Gerbers can be found here: github/alien-die/gerbers

I ordered 5 PCBs on the same site and it cost me $4 with shipping. Incredible!

I also ordered on mouser.com / digikey.com:

• controller - ATTINY2313-20MU
• red-green LEDs - LTSTC195TBJRKT
• switches - EVQ-P2402W
• battery holder - BAT-HLD-001-THM

And when it all comes at once, I realized how hard it will be to solder it all together using my heat gun from Home Depot :-)