Inspired by the modular paddle on the Elecraft KX3, I designed this to directly attached to the (tr)usdx. Combine this with the battery pack from Manuel and you get a very compact CW package. I printed this using PLA. To assemble the wiring I suggest to solder the wires to the stereo plug prior to press fitting the plug into the key to keep from melting the plug hole in the key base.
BOM:
3.5mm stereo plug: Mouser electronics - p/n 490-SP-3533-02; https://www.mouser.com/ProductDetail/Same-Sky/SP-3533-02?qs=%252BEew9%252B0nqrCkfyt%2FFhI%252B5A%3D%3D
0.3x4x10mm spring: Amazon - 240 pcs small compression spring assortment kit; https://www.amazon.com/dp/B0D8SRHGKQ?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_2
20 ga. wire: McMaster Carr - p/n 8054T14; https://www.mcmaster.com/catalog/131/992/8054T14
Ring terminal: McMaster Carr - p/n 8429T11; https://www.mcmaster.com/catalog/131/877/8429T11
M3 hex nut: McMaster Carr - p/n 90591A121; https://www.mcmaster.com/catalog/131/3648/90591A121
M3 washer: McMaster Carr - p/n 91166A210; https://www.mcmaster.com/catalog/131/3692/91166A210
M3 x 12mm screw: McMaster Carr - p/n 92005A122; https://www.mcmaster.com/catalog/131/3455/92005A122
The author marked this model as their own original creation.