Vactrol Capsule by rmdashrf
www.thingiverse.com
NOTE: After some testing, it turns out this design as printed in black PLA isn't perfectly light-proof. Other more opaque filaments (eg white) may be better - testing is ongoing. This is a simple capsule for making DIY "vactrols" - an LED paired with an light dependent resistor (LDR). The default values in this design are for a 5mm LED and a similarly sized GL5516 CdS cell LDR. This design was inspired by the vactrol capules you'll often seen in photos of Nonlinear Circuits (NLC) eurorack moduled build documentation.

I’ve made vactrols in various ways in the past - black electrical tape, heat shrink, other 3D printed enclosures. This is my latest attempt, to use with an NLC Dispersion Delay build (the design is directly inspired by the vactrols seen in photos in the NLC build docs). I like to sand off the end of the LED so it’s flat and superglue it to the LDR, but I’m not sure this is really necessary.

There are other 3D printed vactrol enclosures out there (I’ve tried one or two), but most are bulker than this design, and this one comes with the OpenSCAD source so you can tweak the tolerances as required for your printer and parts.