Shameless self-plug: you could always laser cut the case design I posted. Should cost you around $15 in materials/cutting time. Easy to assemble (glue) and mount the panel (screws or foam tape).
Any idea where can i go online for a CNC or laser cutting service? Not sure where I can look for locally 'cause they're mostly business-to-business service companies ._.
as for what that is: it's a space filler for an iPad shell. I got a complete iPad (Air) for parts and dug out everything inside. Now the LCD kinda bowls inside the vacant space, so that's to fill it up. Cutting the shell for the controller would be another story yet to happen
EDIT: (goodness I've been typing this for too long that I forgot this is supposed to be an edit, not a new comment ,_,)
Also: choosing display bandwidth capabilities should come first, although manufactures got that covered, but the choice of using all DP displays or a mix of both should be part of the consideration as well. You can plug a DP source to a HDMI monitor with a dumb cable, but when you want to connect a HDMI source to a DP display you will need an active adapter, because it's not in HDMI's spec to switch outputs on-board. This is the reason why some DP-to-HDMI adapters cost way more than the cheaper end ones, and also why the cheap ones can't do HDMI source to DP display (and yet one-star reviews still get posted)
I'm not forcing you to an all-DP or an all-HDMI display setup, it's just that this adapter thing, more people should know. (do correct me if I'm wrong anywhere, I'm working on old knowledge off my head. Also those not factoring in about HDMI2.0)