Engine cover securing cap alternatives?

[C.A.R.]

I'm down to zero now.

Those stupid little twist-fit caps which secure the engine cover on (only they don't, cos they work themselves loose) have now all vacated my engine bay.

There are several 'kits' on eBay ranging from £7 for a pattern part set of 4 up to a frankly fuckwit-only purchase of around £20 for some nuts and bolts.

Does anyone know what thread these are, what the thread length / spacer size is and what the diameter of the hole in the engine cover plastic is?

I would measure it, but I don't have my car today.

Thinking this could be done incredibly cheaply, given how cheap stainless steel fasteners are.