This is a free clip with a profile that will snap onto a 4040 extrusion. You can extend or truncate it to fit the needs of your project.
Recommend you not print this in PLA as it will distort over time and lose grip.
Do not just print this clip and check to see if it fits! The grip is very strong and without leverage removing the clip is not easy. If you want to test it first, add something like the tab in the photos so it can be removed.
Files include the FreeCAD design so you can incorporate it into your own projects.