RV Carport Bottom Rail End Cap

I bought and assembled an Arrow RV Carport. To keep furry little critters and bugs out of the bottom tubes, I created an end cap. I used Microsoft 3DBuilder. The carport is built with rectangle tubing and the corners are slightly rounded (just barely). But 3DBuilder doesn't have chamfer, so after printing, I just used a deburring tool to trim a little off the corners that slide into the tube and gently tapped them in. …worked perfectly. 

Just flip it over in your slicer so the closed end is on the plate.

No supports needed.

Print with 100% infill.

Printed with Black PLA.