Where can I sell my PCBs?

[LarryD]

Well . . . the mAH rating of these 1.5V cells are quite low so R2 would need to be increased in value accordingly.

You could have a jumper option for all possibilities

Time for my nightly walk.

Edit

See this for making a case for the instrument:

Share tips you have come across

Making a Reasonable looking Test Jig The following images show how to build a test jig. [A] Design your front panel layout. Print a 1:1 paper copy and add double stick tape. Laminate. [B] [C] [D] [E] [F] [G] Enlarge the holes for your LEDs switches etc. [H] [I] [J] [K] See this post for soldering the proto board components: