Chris Green wrote:

So you want M4, Csk, 1cm (or 10mm) machine screws. You should be able
to find them even at such places as B&Q.

B&Q, screwfix, toolstation don't seem to have them in black though

I'm not certain of the diameter though, they may be M3, so take one
with you to match up. (Or buy a box of mixed metric CSK screws from
eBay).

Measure them as per

https://forums.autodesk.com/t5/image/serverpage/image-id/619695i259CE7C917D9BD7C/image-size/large?v=1.0&px=999

D = diameter M5 (or M4 etc) in mm
L = full length of screw in mm including head