Towel bar mounting bracket (no visible fasteners)

My son wanted a towel bar that was closer to his height, and rather than trying to find a match to the existing metal one, I decided to design an attractive 3D-printable system that let me show off some nice pieces of wood from the workshop. The first one looked so good that I ended up replacing all of them.

I will probably post an instructional video to my YouTube channel at some point, but for now, I included a picture that shows the basic process for installation. These instructions correspond to the numbers in the picture:

1. Install the mounting brackets using the best method for your wall. For drywall, I'm a big fan of these anchors: https://amzn.to/3V6dgGK (Amazon Associate link). They come with #8 x 1 ½" screws, which is the perfect size for this mounting bracket. Note that the middle hole in the mounting bracket is not needed for installation but can help with lining things up with your marks on the wall.
2. Insert a #8 x 1 ½" pan head screw (https://amzn.to/3ToRs7V) into the arm and attach the arm to the mounting bracket. When the pan head screw is pushed back into the arm, there will be just enough poking out to mark an indent in your piece of wood for predrilling the holes in the right spot (or screwing directly into the wood if you're an animal).
3. Attach the arms to your towel bar using #8 x 1 ½" screws. The screws will go 5/8" into the piece of wood, so use a piece of wood that is at least ¾" thick. Tape off the arms and apply a suitable finish like polyurethane to the wooden bar. You can also finish the bar without the arms attached, but they provide a convenient stand for holding the bar while the finish dries.
4. Ensure the extension arms are screwed into the wooden bar with just the right amount of torque so they can still be rotated, and then attach the extension arms to the mounting brackets using the plastic threaded screws. Do both arms simultaneously so it doesn't get stuck. You can also apply a little paste wax to the tip of the extension arm and under the head of the screw to help it rotate easier.

The printing is a little nuanced, but not terribly difficult. I've been printing my extension arms with the narrow end down because this gives the smoothest surface where it meets the wood, and also where the bottom of the pan head screw meets the extension arm. You want low friction on those two parts for easier installation and removal. This obviously complicates bed adhesion, and I had several PETG prints break loose until I started using a 6mm brim and changing the brim gap from 0.2 to 0.

The mounting bracket is recessed on the back to help it sit flush against the wall, which means you'll need to print with supports. For PETG, I set the top Z distance to 0.27 and it came off reasonably easily. The back part will never be seen once installed, so the appearance doesn't matter as much as the structural integrity. You might not even need to remove the supports if you do them sparse enough that they can compress when you tighten the screws.

Print with the seam in the back. As long as you don't mess with the orientation when importing, this should make the seams on the mounting bracket and extension arm line up so you can face them down when installing.

If you want to say thanks, here's my Ko-fi link: https://ko-fi.com/thesnekkershow. Also, post some build pictures. Mine are white and green, but I'm curious what everyone else comes up with.