Step 1: 3D Modeling
I imported the stl file into 123D Make, a free app that lets you prepare your 3d files for laser cutting. I'm using a new preview version of 123D Make that is not available to the public yet, so I had a lot of control over the type of joints to use for my candle holders. The public version of 123D Make will be getting regular updates in the coming moths, so hopefully you will be able to use these features soon too!
In 123D Make, I set the joint type to finger joint with 11 fingers for each joint. I specified the dimensions of my material and 123D Make created 2D vector files with the correct finger size and fit them onto sheets for laser cutting.