Many old power supplies for ham radio applications (Pyramid, Delta, etc.) have exposed heat sinks on the rear, with bare transistor cases that are not grounded. It is easy to short those transistors, damaging the power supply.
This cover slips over the round lid of the transistor package to insulate it from dropped large items, such as coax connectors and cables.
Need 0.4 mm or smaller nozzle
eSun PLA or ABS
does not matter
Duplicate the model and print at least 8 on a plate, so the PLA can cool properly for each layer. PLA works well and tolerates the temperatures for a power supply that is operating within ratings. If you smell cookies, the power supply is overloaded!
STL file is in millimeters, of course!
Caps simply press into place. If you prefer, add a drop of instant-set (CA) glue on the center post then press in place. There is a small ridge inside one edge of the cap that can also hold glue, if you need additional retention.
This design is optimized for the flat top version of TO-3 'diamond' transistor package. It is not necessary to remove the transistor mounting screws, so you will not damage the heat sink compound or internal connections.
Some power supplies have a domed or rounded top on the transistor. These are usually older germanium transistors and may have slightly different dimensions. Use more glue, putting a drop inside the edge with the small lip.
SCAD file is posted, so you can remix to your preferences. If you decide to add plastic to insulate the diamond form base plate, do not put plastic under both mounting screws, as the screws connect the transistor to the interior wiring socket.