If you used magnets, how did you secure them onto the robot?
For magnet bots during prototyping we hold them on with the heads of #8 button-head screws. They are pretty flat.
For final versions we’ll probably make a thin bracket out of aluminum to give it even less of a profile.
We found steel fastners annoying to work with around the magnet. We’ve been prototyping with cable-ties holding the magnet to an aluminum plate.
I haven’t done it yet, but I was planning on using a big piece of heat shrink tubing to attach the magnets to a piece of aluminum then attach that to the bottom of the minibot with a couple of screws
Your milage may vary, but stainless steel screws have been working well for us.