The hands are the key to scale since they are the smallest. I was able to print a .75 scale hand and it looked like it would be ok to assemble. I have a .5 head on my printer so sometimes it is a pain to print super small stuff. By my calculations you would have to print him at 0.686 to get him to be 12 inches tall. So scale the hand to .686 and print on your printer. If you think you can assemble it the rest is easy to assemble once you print all the parts at .686.