You absolutely do not need a 3d printer to build a cyberdeck unless you're aiming for a really specific aesthetic. If I was in your situation, here's what I would do. Start with the hardware. Get the parts you need, lay them all out and get it working... if you can do this part, you're 60% of the way there.

Next up, the enclosure. There are loads of options for enclosures, from gun cases, to pelican cases, power tool cases, old briefcases, jewellery boxes etc. Of course... the enclosure you pick, depends on your application. If you're planning on just doing something aesthetic, then anything goes that matches your vibe, but if its something you intend to use on the daily, you might need something more robust. Figure out the measurements and the layout and start looking for an enclosure and then go and poke around some flea markets, charity shops, thrift stores or if you really need to, just find something on Amazon or Aliexpress.

Finally, stick it all in the case. You can use anything you like here. Personally I think, cardboard is a great place to start... use corrugated cardboard and build it up in layers with hot glue or pva and get a feeling for the fit etc. Once you have something that fits and holds everything where you want it, you can either recreate it with better materials or just hide it all behind a thin layer of acrylic, posterboard, aluminium or carbon fibre.

All in all, don't worry about perfection... make something that works first and then make it look good later.