you can buy the tracks and acrylic and make it yourself if you wanted. Attach the tracks with that liquid that welds plastic together.
Its not too hard either, just have to make sure your spacing & measurements are correct before welding the tracks.
Gemini has some tracks.There are a couple of suppliers here locally that sell the tracks for the cheaper bendy letters.
I know Herring has them, maybe Grimco?
I can look tomorrow.