Add an electrical box to the system only using fireproof polyurethane foam

Add an electrical box to the system only using fireproof polyurethane foam
Normal Polyurethane Foam:
amzn.to/3ZqxmM1
Fireproof polyurethane foam
amzn.to/3RfjLVp
boxes 503:
amzn.to/3Zej80C
5mm plexiglass sheet:
amzn.to/3sNDB00
wd40:
amzn.to/44HlJB7