I used to fix the loo with silicone and then silicone just the cap of one one those screews into the holes where screws should go and tell the customer leave it a few hours before they use the loo else it'll move a bit (I laugh now imagining them stooping over the loo trying not to move it for days - which might just be imaginary but I like to think they're daft sometimes
)
My old man runs a window fitting firm and I used to get a bag of 250 screw caps for about a fiver off him. They're a bit like the ones you'd use on flat-pack stuff, so they have a cross in the back of them which normally would clip into a screw head.
Looks smart, doesn't wobble, no need for drilling and more importantly save a bit of time at the end of the job when you want to get off.