There's no question that I could've used a normal nano cache here but magnetic nanos are just REALLY boring. The manager of the museum where I wanted to place the cache seemed interested in having something a bit different within their grounds so I ran with it!
This cache is able to hold a small RITR log book and a short pencil. The nominal hole diameter is 83mm. The black spacers can be used to fit the cache onto drain pipes of slightly different sizes. I had to use one 3mm spacer and the cache is very tightly held onto the pipe; so tightly that I couldn't rotate it. The cache is fully removable and leaves no trace on the building you mount it to. (This is important as the building it was designed for is a historic landmark in my city)
You may notice the depth of this cache is quite big, that's because it was designed to fit flush against the wall of the intended building. If there's demand I may be able to alter the model to suit what most people want.
No Support material needed
To assemble this you will need:
8 10mm x 2mm Neodynium Magnets
4 M5 x 25mm Bolts
4 M5 Nuts
Sunlu White/ Black
Test fitting before paint