Young's Double Slit Experiment

This is an apparatus for Young's Double Slit Experiment.

This is one of my first designs, so there might be some errors.
There are a few problems that I have to fix. Such as; it gives an error on its stl, and I will give the parts separately which is all together now.

This model should work and fulfill its duty but I haven't printed this yet, but if you do print please let me know what are the results are.