I am at an impasse here as to how to go about creating a larger negative for contact printing from a smaller negative such as a 35mm or MF negs.

I am wanting to do larger prints in the range of 30x36 in Pt/Pl and gum bichromate but the negs I have are to small and I don't have access to LF or ULF cameras yet.

The ideas that I have at this point are to use an enlarger to flash a larger negative to a positive from a 35mm or 6x7 and then flash that to another larger negative to form a negative in the size that I want to work with. I have tried looking for printers in my area that can create a large transparency negative but to no avail.

Any ideas how I can go about this?