Using a cheap micrometer from Northern Tools: My SE shield consists of a 7mil aluminum sheet (approx 1/128", 0.18mm) covered with a 10mil (1/100", 0.254mm) plastic sheet. Either an adhesive backed plastic shield or a sheet of plastic sprayed with contact cement could be adhered to the aluminum.
The closest I can find on Amazon is
a 5mil aluminum sheet, and
2mil adhesive vinyl sheeting.
The plastic sheeting of the SE shield I measured extends beyond the aluminum by a few inches, so, unlike an SE/30 shield, a replacement plastic sheet for the SE would need to be rigid, not flexible like the 2mil sheeting I linked to. Alternatively, I believe an SE/30 shield should work (please correct me if I'm wrong).