Below is a guide on each of the glass locations for the Fingerprinter achievement. Screenshots provided by me, and locations were found by me, with some help from the Revolution Discord. (https://discord.gg/wkESZKDDfE)

Map Name: sp_a1_cube_fling_intro

Most likely the easiest one out of the bunch. Hard to miss. Walk up and claim your prize.

Map Name: sp_a1_bts_wind

You'll likely see it, but it'll be out of reach behind a railing. You need to walk around, hop on a vent, and hug the wall to reach it.

Map Name: sp_a2_end

Look up by the switch to see your target. A simple fling from the wall will do to reach it.

Map Name: sp_a3_vactube_hanging

Simply jump towards it from the light bridge to leave a mark. Don't worry, the cube will catch you on the way down.

Map Name: sp_a4_finale

Out in the open, but very easy to miss with the ticking timer. I missed it twice in my search! You'll need to do a little parkour on the server racks, but it's nothing too hard. Only a 10 second diversion from your real goals.

Congratulations, Janitor!
You're fired. Get out.

Regards,
Stirling