O'Cello Preamp and Pickup Enclosure and Knee Rest

thingiverse

I wanted to use the same electronics used in [petercb's O'Cello build](https://www.thingiverse.com/thing:2863293) and in [my own Mina electric violin build](https://www.thingiverse.com/make:656374), but I didn't want to use any glue in my build (as petercb's build does). Glue makes it harder to reclaim plastic and turn it back into filament. I also wanted to keep all the electronics hidden behind the O'Cello cover and out of the tuning pegs cavity. This knee brace base is designed to work with the knee rest pads from petercb's knee rest design. The holes in my design will fit 3/8" aluminum rods, which should also fit the holes in petercb's knee pad design. I've included the OpenSCAD file for my design, which should make it easy to enlarge or shrink the rod holes in my design as you may have need. I also use the bridge from petercb's design, which has a cutout for the piezo pickup. This enclosure is designed for use with [a CV-210E pickup and preamp](https://www.aliexpress.com/item/32849083156.html). You'll need to remove the preamp faceplate (the screws are behind the label) and the battery cover. There's a cutout in the battery enclosure which allows recharging a 9v battery, [like this one from TalentCell](https://www.amazon.com/gp/product/B07HNKK161/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1), without removing it. The switch cutout is designed for a tension-held rocker switch like [this one on eBay](https://www.ebay.com/itm/2x-On-Off-Switch-Black-Rocker-10A-Small-12V-DC-Tension-Held-Auto-Car-Boat-Truck/182477755984?epid=600716999&hash=item2a7c859650:g:tUUAAOSwfwpcJak6). You'll need to splice the switch into one of the battery terminal wires. See the photos for an example. The screw holes on the preamp seem to have a slight offset. If the screw holes don't line up, try turning the preamp around. If they still don't line up, you might be able to get away without using them at all. The fit around the preamp is fairly snug and its edges should be pressed up against the edges of the electronics cavity, which may keep it from moving around much even without the screws.