V6 holder m3 instead of knurled

I didn't have any "knurled" nuts, and wasn't keen on getting any. So I remixed this part to fit m3-nuts instead. You slide them in from the inside and then just mount as normal. Works great on my printer, good fit, but I imagine there might be some issue on other printers, so I increased the slot just a tiny bit.

The nut will start to spin when overtightened, but it is still rock solid, and works sort of like a mechanism to keep you from overtightening.