Thin PCB replacement, heat resistance plastic?

[Rocksetta]

Along with the NOVA concept of print anywhere, except I would be using a V-One, what thin plastic (~0.2 mm to 0.5 mm) would be a good (cheap) PCB FR4 non fiberglass replacement that can still be baked to melt solder paste to ~200 degrees Celsius?

Any advise about this tape called LUTER 7 $14.99 CAD for printing and solder past baking with the V-One.

Or how about Mylar sheets: Banltre $19.99 CAD 10mil (0.254 mm) Mylar (PET) Sheets or for comparison Baisdy $16.99 CAD

I just found out the recycling symbol for PET or PETE is a 1 inside a triangle. It would be very eco-friendly to get your PCB boards from recycled plastic.

[Rocksetta]

I just tried heating recycled PET to see if some solder paste on it would melt before the PET. It did not

Out of curiosity what is the curing point for the conductive ink and the melting point for most of the V-One solder paste (I think 60 degrees Celsius is the curing point and 200 Degrees Celsius is the solder paste melting point).

I am looking for an easy to find (recycled), solid (not flexible), drillable, thin substrate that can replace the thick FR4 PCB board.

Anyone got any suggestions?

Why do I want it thin? I want to see if I can make a board using recycled material that is thin enough that the copper rivets are not needed. Otherwise I will probably stick to single sided boards, I feel the copper rivets add to much complexity to the process for high school students (think: placing, hammering, loose rivets, soldering rivet to trace, cracked boards, etc etc).

Can anyone think of a common very thin material that can heat to the solder paste melting point?