This is a bracket to hang small float switches (water level sensors). I use it to hang from a glass baffle in my sump. Can also hang from a bare aquarium wall. 

It is customizable in Autodesk Fusion 360 (free hobby version):

• depth
• width
• neck diameter of your switch
• number of clips
• glass thickness

To customize:

• open the .f3d file in Fusion 360
• Solids panel → Modify → Change Parameters
• modify any of the values, changes should be reflected immediately 
• File → Export → export a .step file
• open the .step file in your slicer and print

To print

• print on its side with clips opening upwards
• organic supports if your slicer supports
• 0.3mm layer height is fine
• I used PETG as seems safer for aquariums