The handset retention tab for Cisco 6821 model phones. Since Cisco in their infinite wisdom has seen fit not to sell just this part, which is VERY easily lost when setting up the phone...

Ender 3 v2 settings: Whatever PLA (should be fine for any environment a VoIP phone will be OK living in) Tree support Raft 100% infill .10mm layer height 30mm/s for that definition cuz my printer shaky af

Requires very minimal post processing to fit nice and snug in the phone. Mostly cleaning up supports.

Probably prints beautifully on resin printers, I don't know... But my tired old Ender can't print the very small retention bumps on the side. It's still a snug enough fit to not fall out when shaken or lightly manipulated, but a nice high res SLA printer would probably bust those tabs out just fine. It still takes a fair bit of force to pull them out and can be difficult to do it without a pliers or something.