Download the stupid simple code from my server here. It's written in C. It ought to compile and run without issue on any flavor of linux with basic C libraries and gcc.

At the moment, critical parameters (such as circle diameter and slot length) may be configured by changing the #define statements at the beginning of the code. Ugly, but effective.

The cut out shape is quite flexible on its own.  But to maintain a bent shape, ideally you'd soften the piece (both thermoplastics and MDF soften well with hot water) and press it in a "die" until it cools/dries/hardens.  The form I have in the pictures was made using a very simple CAD solid part imported into 123Make, which generates the files to cut out all the pieces.