Decide on a geometric model to build, such as a cube, pyramid or prism.
Push one tip of a toothpick halfway through a gumdrop. Repeat for the other end of the toothpick so that there is a gumdrop on both ends. This is your first line segment. Place it on the paper plate.
Continue assembling toothpicks and gumdrops to form the base of your geometric model. The base will be laid flat on the paper plate and resemble a 2-D drawing of the model's base. For instance, if you are building a triangular pyramid, the base will be a triangle composed of three toothpicks joined by three gumdrop vertices.
Build the model up from the base using more toothpicks and gumdrops. For example, if you are building a pyramid you will insert one toothpick in each of the triangle base's three vertices. These three newly inserted toothpicks should each point upwards and towards the center of the triangle base. Join the three toothpicks with a gumdrop at the top center of the pyramid.