[Al Skierkiewicz]

There are two parts of the rules that come into play here in my opinion...

"b. Prefabricated and/or Preformed COTS plastics or metal are not permitted (i.e. buckets, cups, grippers, gears, etc.).
1. Plastic or metal sheet, plastic spacers, and extruded aluminum are not considered to be prefabricated and are allowed with no restrictions on dimension or quantity provided no other rules are violated."

and...

"d. The following additional structural parts, fasteners, and materials are allowed provided that they don’t violate other rules, such as safety, entanglement, <R03>, etc. This includes no limits on quantity and size of the following materials:
1. Raw Material (e.g. metal, plastic, etc.) provided that it is readily available to all teams from standard distributors (e.g. McMaster-Carr, Home Depot, Grainger, etc.). The definition of Raw Material are items before being processed or manufactured into a functional form."

I think that both these rules point inspectors to look at materials in their purchased "raw" forms. A sheet can be cut but is still identifiable as a sheet. A sheet melted into another form is no longer identifiable as a sheet. The linked video seems to contradict this but FTC must come out with a statement that 3D printing is allowed before it can be stated as a legal method.