Using this plug, you can store stuff inside the steerer tube of a mountain bike. This is the hollow space inside the headtube of the bike. The plug goes in the
...Zeig mehr underside of the steerer (top of the fork). It will fit a 1.5" tapered head tube. On my bike this gives approximately 1.25 x 5.5 inch cylinder of storage space. I can fit a CO2 inflation and a couple of thin tire levers.
If you don't want to print with flexible material for the 'seal', you can use some rubber o rings or a piece of foam cut into a ring shape. I tired this and it worked well with all three seal solutions.
The bolt I used is a 3mm (M3 x 15mm). I used two nuts but there are a few ways you could do this. Print the wing nut if you want to make it 'tool-less' to open.