Instructions 1- Purchase a train that fits the tracks that the child you are purchasing for is using. I have girls, so I did not know that the trains are not 'one size fits all tracks'. 2- Remove the face. The Thomas Wooden Railroad faces are attached with two pins at 3:00 and 9:00, or just under the eyes on most trains. You can just drill or dremel them out or you can walk an exacto in if you want to keep the face. Once you've removed the pins, the tab at the bottom just pops out pretty easily. 3- Measure the diameter of the face and the width of the shelf at the top of the cattle catcher. 4- Obtain a scan of the subject child's face. You can scan them if they will sit still long enough. Probably not going to happen with most little kids unless you scan them in their sleep. I used Photo2Mesh to convert a photo to a raised 3D image. 5- Create another model that is a cylinder with a mounting flat on the bottom. I've attached an stl that works with Thomas, Charlie, and Rosie. I'm an Alibre user, so my parametric model probably won't be useful to many. 6- Use the cylinder shape to slice the face model. 7- Boolean the face model to the cylinder shape. 8- Print it. You're probably going to want to try to hit at least 80 microns. 50 microns is ideal. I have to admit, I had a heck of a time getting this to print and you can see that it is messed up at the bottom. I ended up merging the whole thing with a very thin cylinder and printing the first layers really slow. 9- Glue to train face. I printed mine in ABS. Acetone worked great. 10- Present to child and watch their face light up : ) Print at 0.2 mm layer height, with 10% infill. This uses 1 g of filament and takes 8 minutes.