Here is a cover for the connection point between the front diff and propshaft on a Honda Acty.

I removed my propshaft to disable 4wd, and I wanted to cover up the connection point on the front differential.

Use M8 20mm bolts with washers to attach.

Check out the 3mf file for print settings. Essentially you want 9+ perimeters, 16 bottom layers at .2mm layer height, and around 8 top layers. I used ABS, but any other tough and temp resistant filament should do the job. I wouldn't use PLA.