I could not figure out how to send a diagram
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Ignore it.
Ok, here's a list with suggested Digikey order codes for one prototype target :-
2 off photocell PDV-8103-ND
1 off opamp LM324NFS-ND
1 off 100k pot CT2268-ND
1 off 100k trimmer 3319P-104-ND
1 off ceramic cap 399-9776-ND
1 off 2.2k resistor CF14JT2K20CT
1 off 10k resistor CF14JT10K0CT-ND
1 off 470k resistor CF14JT470KCT-ND
2 off 3-way terminal blocks A98334-ND
1 off 100 ft reel 24AWG hook-up wire C2003B-100-ND
1 off small pack 60/40 rosin-cored leaded solder 473-1160-ND [Observe health precautions when using]
Total list cost (excl shipping etc) = $27.48.
The most expensive item is the wire ($14.83). You will need only 2 ft or so of this type per board for jumpers between components, hence ~ 32 ft for all 16 boards. Cheaper loudspeaker wire, or low-current mains wire , will be ok for running the 3 'bus' wires between boards and for interconnecting the 4 panels.
I could not find a suitable strip-board listed by Digikey so you would have to source that elsewhere.