I recently bought my first Hornby HM7000 Sound Decoder for a Hornby OO Class 50 Diesel Loco, when I bought it I purchased the power bank for it.

When I went to fit none of the enclosures really worked with the power bank. The largest one available was great but left no room for the power bank so I drew a smaller enclosure for the speaker but with an area to sit the power bank. This is the design I came up with, It fitted perfectly in the loco and the sound still works really well. So I thought it was worth sharing for other people to use.

I have included a STL file with the supports added so you can use it to print or see the best orientation for printing.

For printing I would recommend it gets printed on a 3D resin printer.