https://sekrit.math.com/exam/<SID>_random_hex.pdf
" a few days before the test. At 11am (test start), I put those files in place and tell students to begin. 35 mins later, they stop writing and scan. They then upload to our LMS (Canvas). I then pull all those PDFs from Canvas (using the LMS's API) and scan them into Plom using plom-hwscan
(we call this "Homework Mode" in Plom)