Here we have what you would call a Mini multi use vice I guess, you can use the vice as it is or fit the jaw adapters which are reversible for different components or add the pins which can grip circular objects.

The hardware I have used purely because I had them to hand and they are the 5mm low profile Allen head bolts, I purchased an assortment of these bolts from Ooznest UK ages ago But Openbuilds are the main supplier I believe, standard Allen head bolts should be ok to use as well but I don't have any to try, I used a 5mm grub screw to sold the screw thread adapter in place, but an Allen head bolt would work too.

There are 4No slotted holes so it can be secured to a board or bench top or just use it as a hand vice.

Another great design project.

Thanks for looking.