Some things to look into if possible,
1) Temperature behind motherboard if adding a M.2 SSD there. General motherboard/case temperature?
2) Dust filtering. Material is aluminium, so no magnet dust filters will work. Adhesive Demciflex needed it seems.
3) Panel thickness. If panels are too thin, they will inevitably bend, like on Ncase M1.
4) Panel seating. Current plastic clips can break, or wear with the consequence that they don't hold in the panel perfectly.
5) Stiff USB 3.0 cable. These are often too long, and often too stiff. Not fun.
6) Perforation pattern on the side panels. Some patterns cause more noise than others. Not sure if it matters here or not.
Some of the above things have annoyed me with the Ncase M1 that I own. I don't know if there are better solutions available. Just want to raise the concern again.
Otherwise, great job, and hope to buy this case.
Regular msata or m.2 drives which do not get very warm would most likely work. On the other hand, the Samsung XP941 or SM951 probably would not work as they get super toasty without proper airflow.