I was constantly picking up cables from the floor next to my desk. I tried one of those spiral-type cable holders, but they didn't work for me (not taking a jab at them... just didn't work in my situation). So I made this.

This is a cable holder that uses magnets to hold cables in place. An angled piece is printed with "fingers" like a comb. This part is what gets mounted to the desk. It has magnets embedded in the bottom of it. Once the cables are in place, a top plate with identical "fingers" comes from the other side to cover the slots of the angled piece. A set of magnets in the top plate attract to the magnets in the bottom angled piece. This holds the cables in place.

My design criteria:
-three slots for a 4mm cable
-two slots for a 5.5mm cable
-I used the Harbor Freight rare earth magnets (come in a tube with, like, 10 of them). The hole accepts up to 2mm thick, 9mm diameter magnets.
-I set up the combs such that the magnets cannot be physically touching each other. I wasn't sure how strong the superglue was and didn't want the magnets constantly coming out. The 3mm printed space between the two magnets is strong enough to hold, but easy enough to pull apart.
-I am using a 3M hook and loop tape to hold it to the desk.

A tip, I pulled out all four magnets and laid them on a table with the same pole facing upward. I put a black dot with a Sharpie on it so I didn't lose track of the side. I would hate to get the magnets glued into the holes upside down.