The holes are near 120mm ( 115mm ) so they line up with the front intake fans.
Instead of just backing them with mesh, i went for speaker mesh/grilles as they are slightly curved and would mean i could 'flush' mount them to the acrylic.
Black, before
White, after a bit of spraying.
To flush mount them i had to pin them at the right height whilst the glue dried. I used silicone sealant for this, as it holds as well as glue would, but can easily be removed leaving no residue on the acrylic.
First test fit, with tubing roughly placed to show thw colour scheme on the inside Purple/White. Have used 3mm white LEDS and bezels ( like i have on the HDD coolers earlier ) for some internal lighting.