I'm a chemistry teacher, and have been making 3d-printed manipulatives with embedded magnets (which stick to the whiteboard). I've done a set of physics vectors w/ labels, and chromosomes for biology. Now I'm designing a set for teaching VSEPR shapes on the whiteboard. They'll be 2d, with atoms, bonds (in-plane, wedges and dashes). SO. Which type of dash would you want your set to have???