Looking to add insulation between a TO package-type device and a PCB?
Component Insulators, Mounts, Spacers | Electronic Components Distributor DigiKey
Digi-Key has several options for many different TO package-style devices. Here are some examples.
TO-3
TO-5
TO-5
TO-18
TO-66
TO-100
TO-202
TO-218
TO-220
TO-220
TO-247