Credit to Devin Sidell (https://grabcad.com/library/steam-deck-shell-1)

This model is not quite complete. some fitment issues and in general its missing a lot of the inner engineering that went into the OEM steam deck shell. It is functional and should hold the components but for instance, the back buttons will be loose without “spring” to them. Front shell is untested as of yet. If you're brave and would like to waste some resin, go for it.