I have some metal film 1/2w 2.2ohm resistors in some car wiring. I’m concerned about the durability of this install and am seeking advice on how to protect the resistor once it’s soldered in place. The obvious is heat shrink tubing, but it’s there anything more substantial?

I’ll be using these resistors in a custom pigtail that will plug into the car wiring. 3D printed housing? I have tried searching and I haven’t found anything like that.