super basic safety cover specifically for a TBSsourceone 7inch V3 arm bolt.   I didnt like how the sharp threads were going to rub the motor wires as i was fixing to solder them to the racewire.  This simple cap threads onto the exposed bolt, but will use a little silicon sealant to fix them to the arm.  I will likely publish a few more versions of this, but the one that worked for me was about 2mm deep.