Those silicone containers are made specially to transport cannabis resin.....no joke! They have similar tact than real mouse balls and the inside cavity is spherical.
The diameter is 31mm outer and 22mm inside. Once filled with the appropriate iron ball it weights more than enough.
They only have two drawbacks:
The cavity is not centred so if you throw it to rode it makes odd movements like Humpty Dumpty...Not a great problem as the movement of a mouse is usually gently.
The other is a little plane in one of the halves to prevent it rolling when stand up (you can see it on the white-black ball), but I'll try to add some of the same material and then complete the shape grinding it , as I have already done with the burrs of the purple one.
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About the pulleys I have found cheap 14mm or 15mm dia. tap joints, but they are only 4mm thick, enough with the new ball's conditions I suppose.... The inner dia. is also 4mm, but then they can be pushed in place without glue.
I don't have a Patkany so I don't know if they will fit, but better than nothing.
