Trailer Hitch Receiver Cap Pin (Parametric!)

PLEASE NOTE: If you use the Customize feature, you'll get an STL or a 3MF file. The 3MF will be set to print in PLA Basic with the 0.20 Standard Profile. You will want to change the material to something more suitable for this model, as noted below, and also increase the number of walls. My profile uses 6 walls. I would recommend you change to that. Go higher if you wish.

UPDATE (20 Dec 2025): As part of my efforts to learn OnShape, I also modeled these over there . Feel free to have a look, gain inspiration, whatever.

So, you're hot to print one of the many custom trailer hitch receiver covers, eh? Some have built-in retaining mechanisms on flexible “arms”, others just have a hole that's intended to line up with your hitch receiver's side holes. Cool - but how will you secure that cap once you stuff it in the receiver hole? Here you go!

There are 2 variants here. 1 has hex nuts on the ends, while the other has round ends with knurling. No, you're not crazy, these are threaded backwards. I followed the example of someone else I saw making a similar part, using a left-handed thread. Why? It should give you a few extra moments of security if someone's trying to steal your cap. Either they'll get frustrated, or at least you got to mess with them first. :)

The models in the provided profile are setup with a 78mm pin length. That's plenty for MY hitch, which is a Curt Class 3 hitch. You might want to measure the width of your receiver tube before you print. If you want to adjust the length, please grab the Fusion file or use Makerworld's customize feature to change the parameter that governs the length of the pin.

Please note: While my profile is fairly beefy, using 6 walls, THIS IS NOT A LOAD-BEARING pin. It's only there to keep your receiver cap from falling out. If you put load on it, it will probably snap. You'll need to print this out of some sort of material that's suitable for outdoor use. Think PETG, PCTG, PA, PC, or my personal choice - ASA.

The prints shown in the pics were run in Polymaker ASA.