Up here is the finally product of a relatively simple-to-make, easily printable Christmas tree cookie ornament. There are three major components to this project: The cookie, the sprinkles, and the hook.
Step 1: Step 1: the Cookie
This cookie shape comes out best if you do it somewhat randomly. First, take a half dome shape, and expand it to the size of a full cookie. Secondly, create more half domes, ensuring that they are irregular, and place them around the edges of the first, larger dome until the cookie looks natural. Then, take some cylindrical holes, and put them all in one area, but stagger them out, so it looks as if somebody has taken a bite out of the cookie. Group all of these shapes together and you have the base for your ornament.
Step 2: Step 2: the Hook
Every ornament needs to be hung on a tree somehow, right? This particular ornament's hook is very simple: a low cylinder, no higher than the cookie's top point, with a cylindrical hole placed slightly off-center will create an easy-to-use hook for the tree branch.
Step 3: Step 3: the Sprinkles
These are the most difficult part. Firstly, in the picture, there is not just one, but three groups of sprinkles. This is to help with colored printing, if that option is available. This must all be completed on the original cookie base. Each sprinkle is the same half-cylindrical roof shape; however, each one is on its own plane, somewhere horizontal and connected with the cookie. They must be grouped randomly enough for the colors to be believable, so go through and put all the sprinkles on, then go back through and regroup them depending on what looks the best.
Step 4: Step 4: Put It Together!
This is simple. The sprinkles are already on the cookie (since that's the best way to work), so all that you need to do is drag-and-drop the hook onto an appropriate piece of the cookie. Voila! Your ornament is finished. Included in this step are an .stl file for single color printing, and a .vrml file for multicolor printing.