Probably the best fridge pen(cil) holder

Seems like I accidentally created the most convenient fridge tool to hold your pen or pencil on the fridge or other metal object (said by my wife).

Included are adapters for 10x10x10mm and 30x10x5mm magnets.

You can find manual on how to make an adapter for your own magnet size below.

Pros of this design:

• It is comfortable to take out pen or pencil
• Will hold pen even if tilted significantly. 80° is still fine with many pen shapes
• Compatible with many magnet sizes (max size is 30,2 x 14,2 x 10,2 mm)
• Durable
• If you use strong magnet, you can use it as fridge door handle :) 

What you need:

• Magnet
• Glue (best is 2part epoxy glue)
• Highly recommended - ordinary 50mm wide tape

How to create adapter for your specific magnet?

Hole in the holder has designed dimensions 30,5x14,5x10,5 mm and I use outer adapter sizes of 30,1x14,1x10 mm.

So just create a 30,1x14,1x10 mm block in your 3D software (or in PrusaSlicer) and subtract a hole for your magnet from 30,1x14,1 side. On MK4 I use 0,15mm as a tolerance from all sides. So include tolerances based on your printer and filament setup.

Gluing:

I recommend 2 part epoxy glue (what I have tested with best results), but if you print from PETG, you can use PVC pipe glue, but contact side might not be so nice and smooth.

1. Put glue on the inside of the holder + outside of the adapter
2. Slide adapter to the holder
3. Put glue inside of the adapter and on the magnet
4. Put a tape on metal surface
5. Press firmly whole assembly onto the tape and squeeze all glue from the inside. Recommended orientation for this step is as on the picture below (magnet pointing down). You might need to clean some glue from the corners once the glue dries.
6. Wait until the glue dries
7. Remove the holder from the tape. Usually glues don't stick to the tape, so it should be fine, but if you are in doubt, test glue on the tape first.
8. Done. Enjoy the convenience :)

My print settings:

- printer: Prusa MK4S
- layer height: 0.2mm
- sheet: Powder coated
- nozzle diameter: 0.4mm
- print orientation: as on the picture
- material: White PETG
- supports: no need
- perimeters: 3
- solid layers (top/bottom): 5/4

If you want, @AR_3DPrint_1965246 made an extension to also hold a piece of paper.

(I don't need it, but might be useful for someone)

It can be found here: https://www.printables.com/model/1280543-stifthalter-mit-klemme-fur-notizen-oder-einkaufsze 

I just use the “magnet power” to hold the paper in case it's necessary.