I recently got a sewing machine that was missing its compartment box, so I cadded one up. Hopefully this helps someone in a similar situation. This one is a copy of the one here:

Extension Table Accessory Compartment Singer #V880065210 (singeronline.com)

Here's a link to the onshape model in case you have a different compartment and want to make adjustments.  

[https://cad.onshape.com/documents/2c3f3038454840c433d5d3ae/w/871d27463e031c89b39ad0f7/e/18bc5997d6bb6f7397a90588?renderMode=0&uiState=66dcdce6bf94e2384717ba70](https://cad.onshape.com/documents/2c3f3038454840c433d5d3ae/w/871d27463e031c89b39ad0f7/e/18bc5997d6bb6f7397a90588?renderMode=0&uiState=66dcdce6bf94e2384717ba70)

The cover attaches to the box with nub hinges at the bottom.