When you say 'slip/rotation' do you mean they turn 'sideways' inside the strap (so that the flat part of the 'D' becomes visible and the rounded part disappears inside the strap)? In my experience, the straps should be tight enough once the rivet is in to disallow that - they're quite short. Or do you mean the D-rings swivel
around the flat part? In which case they should absolutely do that until the laces are tightened.
I used leather for my straps and the D-rings are quite tightly held. Like you, I used Chicago screws, and
joberg is quite right, you'll need to paint them if you want them white. Mine are painted with a good primer and then three coats of gloss white acrylic, as are the D-rings.
View attachment 1862395
View attachment 1862396Hello! Nice work! What are the length of your straps? and what dimensions for rivets?