I tested it today but doesnt work.
The weight below the bearings is too high and the idea of a pla slide axis is just not smooth enough to let it spin.
PROTO6 will deal with this problem and with the length from cut point to bearing (Scalpel blade =4cm) so the blade should fit into a bearing
PROTO3 is enable to cut but it doesnt get the Corners right. PROTO4 will need to get a good offset setting AND blade height setting.
It uses some springs which fit between the inner and outer shell, but you need to fit some toothpicks in the inner shell (Prototyp). I test it in the next days and change the description and upload some Photos.
You just need some springs ( I bought some but you can fit there some pen springs)
Normal Bearings (you know these skateboard ones)
Toothpicks (There are 4 Holes but with my springs I just use 2)
M2,5 and M1 screws (I add the length later)
maybe some hot glue to fit the bearings (my Axis is slightly smaller because I got some with 7,5mm diameter)
of course you need to sand some parts (the shells)
And i forgot it uses these scalpel knifes you can tweek the blade offset with the Frankenstein construction.