A clamp, with a simple design and fast to print
It is the design for a clamp, with a simple design and fast to print. It is quite to print (around 36 min) and it does not need printing supports.
For having a higher strength, it can be printed with more walls and with a higher percent of infill, or in PETG.
It uses a previously available nut and bolt (https://www.thingiverse.com/thing:193647)
Update: A stronger version of the clamp was redesigned. You should use better the improved version (Clamp-Simple-2.stl)