Scored a bucket of these from a long defunct audio company. It is pretty good experimenting with different coloured LEDs and different LDRs. Some to look for are GL5549, which have 10M-15M off resistance, and GL5516, which is about 5M.
Off resistance is important when using vactrols in VCAs and panners...which is something I have been doing a lot of lately. Of course the speed in getting there is important too, but that is more critical in LPGs.
Anyway just putting some pictures up, in the hopes that
1. someone knows where to buy these (please comment)
2. someone with a 3d printer decides to make some (again please comment)
update - flab on muffs has developed a great looking 3d printer design