I got tired of the awful flex-arm that came with my Plugable USB microscope, so I designed my own. This design uses a rack and pinion for height adjustment and secures to the USB microscope using two clamps. The rack and pinion allows for really tight adjustment without throwing the lens completely off-target.

Yes, it is completely overbuilt.

Note: If the clamps are a bit loose for your microscope, try shimming them with painter's tape.

Required hardware: 1x 2020 extrusion, 15.6cm (vertical arm) 1x 2020 extrusion, 14cm 2x 2020 extrusion, 21cm 4x 2020 corner bracket + bolt and T-nut/hammer nut 3x M5x10 1x M5x35 2x M5 nut 1x 625RS bearing (common in Creality V-slot wheels) 3x M5 T-nut or hammer nut 2x 4mmx150mm hardened steel rods

Optional hardware (for cable loop): 2x M3x10 2x M3 T-nut or hammer nut

If you want to secure the observation platform to the 2020 extrusion frame like I did, you can simply drill two 1/8" holes that line up with your extrusions, then use 2x M3x8 and 2x M3 T-nuts or hammer nuts to secure it. You can raise the base up around 2mm to allow the base plate to slip underneath it.