Excellent idea for the bathroom. This design includes drain holes on the bottom, and personal monogrammed touches. Space for two toothbrushes and toothpaste.
Step 1: First Design.
I used TinkerCad.com to design this instructable. Very easy. Very Basic. That's the beauty of it. Start with the base and extract it vertically.
Step 2: Design With Dimensions.
Next, Design with dimensions. Simply double click on the dimensions you've made and adjust them accordingly. The design I used will accommodate battery operated toothbrushes as well.
Step 3: Overview
Next, I clarified the orthographic representation by adding the necessary views. Specifically, the top, front, side, and isometric views.
Step 4: Printing
Ta-daaaa! Print it using a multi-colored printer or just one. I printed this one with a single filament printer, the Makerbot 2x. It's simple to make it look like I used an expensive printer. After your design has been printing for a few minutes, simply pause the printing, change filaments, and continue. I did this for a total of 4 colors and it turned out great!