If you can scan the pland in to your PC and also have access to a laser printer the solution is at hand.
Print the plans out on the laser printer, put the print face down onto the wood/plastic or what ever, and iron it with a warm cloths iron. If you flip the image befor you print it out that text will also be the right way round!
The 'ink' in laser printers is thermoplastic toner, thus ideal for doing warm transfers with.
And you can print a line only a fwe pixels thin, so nice and accurat too.