You can 3d print the following enclosure for your Portapack (click the pictures to get the design files):

And the following magnetic cover:

If you do not own a 3d printer, you have other options:

• Weerg for a high quality print
• 3DHubs for a low cost alternative
• Tindie another alternative, with a lot of customization options
• Injection moulded version of the case

If you need a different design, or material, check more options directly in Aliexpress.

For a comparison between the results of the different fabrication techniques, check: https://youtu.be/lB-vc-Y13PM

Assembly

Check the assembly.pdf from the case files for instructions.

Speaker

You can easily place a small 8ohm 1.5W (14x21x5.5 mm) speaker inside. There is no holes in the case but it seems that the sound quality actually improves with the case: https://www.youtube.com/watch?v=XkaGV9muvbg

Check more details about the speaker wiring here.