New build with recycled parts on a ridiculous budget 120cm*60cm work area

[Zeeflyboy]

Yeah I've used the self tapping thread screws before, albeit m6 rather than m12. As you say they have a cutting type thread rather than the typical. Work well though, especially when you have a lot to do it's a big time saver over tapping.

your extrusion holes are a slightly different design to mine and looks easier to tap with those "tabs", I just know that even tapping mine to m12 was quite an effort. I just imagine you might risk shearing a bolt off trying to drive a thread that big with a normal bolt using an impact driver.... which might probably ruin your day, although m12 is quite meaty so that would take a lot of force I guess.

If you were closer you could have just borrowed my taps, but I guess just posting them to you won't work out much cheaper or quicker. No one near you that you could borrow from?