Free and easy to use CAD software
It’s the simplest, quickest way to design simple parts for 3D printing. It’s web based, with nothing to download. To use it, you drag basic 3D shapes (cubes, cylinders, cones, spheres, etc.) into the work area, where you can stretch, shrink, move, rotate, and merge them. Then you can output the design as STL file for 3D printing (once you run it through Slic3r to generate tool paths for the printer you’re using). You can also click a button and order a 3D print from a service bureau.
Here’s a recent thing I printed: a wall-mount centrifuge tube holder. A while back I bought a pack of 50 tubes from Amazon, because my daughter and I became interested in Geotagging. We soon lost interest. I considered throwing the bag of tubes away, but then decided I could use them to hold nails, screws, nuts, picture-hanging hardware, etc. So I designed a wall-mount tube holder in Tinkercad and 3D printed a bunch. Now I have easy access to small parts.10/5/17