Gentlemen, this is the small version of a Case traction engine. I used the plans from my 1/12 Case engine and scaled it down. It's about 1/75 scale. Just a little larger than HO. It will run on compressed air but the piping is so restrictive that will only run on about 25 lbs. Most of the small fasteners are 1x.25 mm. The hardest part was making the rear wheels. Being that the cleats are layed out at an angle to the wheel axis I couldn't just turn them at an angle and cut them. I mounted the stock in my dividing head, turned the head at the appropriate angle then cut one side of each cleat with a degree cutter, then repeated that for the other side of the cleat. I then made a cut between each of the cuts to remove the extra material. The dividing head was then turned to do the other row, same procedure. After machining I went back in between each cleat and filed the contour with a needle file.