Last year I built a Hadley telescope, which is a 3d printed structure with some inexpensive optics from China. https://www.printables.com/model/224383-astronom

Last year I built a Hadley telescope, which is a 3d printed structure with some inexpensive optics from China. https://www.printables.com/model/224383-astronomical-telescope-hadley-an-easy-assembly-hig https://www.printables.com/model/224383-astronomical-telesco... One of the things that surprised me, being new to telescopes (and certainly never having built one) was that it was deemed better to leave dust on the optics than to potentially damage them by trying to clean them. The dust just doesn't affect image quality. I had no ide athat would scale up to gunshots however! Very impressive.