I'm about to start the O scale Steel and Pipe kit. I tried printing it on two sheets of card taped together to accommodate the 14 inch length, as instructed, but had problems.

So in the end I simply printed at 97% on to standard A4 (210mm x 297mm) 210gsm card. Everything fitted, and the difference in size is unnoticeable.

Scott;
Sounds as if you creatively solved the problem. You are right, no one will pick up
on the 97% vs. 100%.

If you were to use an EPSON Workforce printer, they print on 17" card stock easily.
(17" card stock is available as Bristol in pads at Michael's and other art stores).

Some printers have a "banner" mode which allows even longer sheets.

Otherwise it is not too difficult to join two sheets by splicing AFTER printing.

Well, I gave it another go (for another image altogether, not a Clever kit) and specified 210mm x 594mm (i.e. 2 x A4 butted on the short edge) to the printer. It worked perfectly !!!