These are the STL files for printing the frame.

You will need to print two of the top/bottom, and one of each side

The source is availale at:

https://cad.onshape.com/documents/ba47819ff100597297d1d967/w/f19409ec7cd5459afb429cb9/e/a0e0cc37dee6fb879c4bcc2b
https://cad.onshape.com/documents/5374160b1b209f298471bf23/w/77e97d7333356f1dcfe6c902/e/6c75800e116cf1f6a984aaa4
https://cad.onshape.com/documents/1e544928f336f4755d6edfbe/w/b9582e1314647916bddf672c/e/41923e90fc3648cd04399c0e