The Irwin Quick-Grip clamps are great, but if used vertically with the long end pointing up then they are, quite frankly, an accident waiting to happen. The clamps work well but the bare metal ends are hard to see and could easily take your eye out.

I've seen many YouTube videos where makers have put coloured tape on the ends, but what the heck, here's a push on cover that a) increases the visibility and b) should prevent serious injury if you were to smack your face into it.

Obviously I can't give any guarantees, but here's a 1" diameter plastic disk that is going to do a lot less damage to your face than the 1/2" x 4.6mm metal rod (British child of the 70's, I'll use both units if I want to).

OpenSCAD included if you want to adjust it, but this size fits snugly on my clamps.

Print in a bright colour. I have yellow on order, black (as shown) was purely because that's what was in the printer whilst I trimmed this in, but visibility is key here.