Time Timer Magnetic Mount

Yes, I could've glued the magnets to the back of it without a housing, but where's the fun in that?

Print it however you like, it'll be under extremely low load during its life unless you mount it directly over a burner on your range.

I included two stl files, one with magnet holes (8x3mm) and one without. I also included the step file and a link to the onshape project. 

I printed mine in PETG because that's what I have on hand. No supports are required. As far as magnets are concerned, you can use x6 8x3mm magnets, modify the model in your favorite CAD software, or use a modifier in your favorite slicer to make empty space for your magnets. I used 0.28mm layer heights. Infill % is up to you.

I'm not thrilled to admit that this took a lot more iterations that I would've liked to find the right amount of magnets required. I tried x4 6x2mm, x6 6x2mm, and x9 6x2mm magnets. None were strong enough to keep it from sliding down a vertical service. The strongest magnet I had in my collection (without thickening up the model unnecessarily) was 8x3mm. It appears that x6 of those is enough to keep it from sliding. I kept 9 holes on the back just in case. I oversized the holes 0.3mm which results in a loose friction fit. I recommend gluing the magnets in place if you use the model with existing holes.