Bulb Finger Joints are useful and attractive co-planer joints for connecting different sheet materials which are very easy to produce with machines such as CNC routers, Water Jets & Lasers. A great benefit of these joints is the strength along the plane of the joint without having to glue/ weld.
This Instructable shows the simple geometry behind this joint and explains how to draft this & how you can adapt its form to allow for greater control of the technique and hence the overall design.
I'm explaining this in terms of drafting it with programs that can export to the manufacturing tools capable of fabricating these components, though the form can be achieved with a basic compass set.
Thank You TechShop Detroit for helping me with this design :) www.techshop.ws