My Singer 4423 sewing machine was missing the bobbin cover, so I measured and printed this. I think this will fit the following models: 3321, 3323, 4411, 4423, 4432, 5511 Scholastic, 5532 Heavy Duty, 511, and 554. That's just a guess by comparing to replacement parts online.

I had a little bit of a tight fit with the back right corner when attempting to fit it in, but after I got it to fit in once, it has been able to come in/out pretty easily.

I've also added an opening on the right hand side to use a fingernail to pull the cover off if needed.