Baby Crib Mobile Arm

V2 update:

I needed the arm to be a bit taller, so I had to make it in 2 parts to fit in my printer. The design is parametric, if you have access to fusion, you can open and adjust the variables to make it fit.
To attach the 2 parts you can either use a large wood screw, or an M5. I had better lock with wood screw. I sanded the bed side of the part with a course sand. Print it with Mat PLA, it's easier to sand. 

V1: 
I have 2 sizes already exported, one for a 300x300 bed size and one for 250x250. 
You can open the parametric file and adjust it to your liking, the picture is the medium size. 

It attaches securely using a simple screw and washer. I printed in Matt PLA. 
The design is optimized for easy printing and good bed adhesion, so one side has a slight flat side. depending on where on the bed you're mounting it, you can flip it so the “bad” side can be hidden. 

The round profile can be changed to a square profile in the parametric file.