Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4087094.
I needed an adapter to be able to hook up my dust collector (https://www.thingiverse.com/make:724045) to my Dewalt 735x Planer. The connection on the planer didn't fit the hose that came with my Ridgid Vac. I designed the adapter with two female ends to fit the planer and the hose.
I made this using CadQuery (https://github.com/dcowden/cadquery or https://github.com/CadQuery/cadquery) and FreeCAD. All of the diameters, lengths, and thickness are easily adjusted.
The adapter has tapered connections at each end, meant to fit the slightly tapered hose and planer connection. By being tapered, they still fit snugly if the diameters are a little off (any error just changes how far the hoses seat into the adapter). The taper I used was 1/20 (1mm change in diameter per 20mm of length - very slight taper). While the taper will overcome differences in diameters, I wanted to make the adapter short, so I needed a few tests to get the depth of insertion right (0.2mm change in diameter changed ~10-15mm depth of insertion).
The CadQuery file allows you to change the sizes, and to print test rings (3.5mm deep) to verify the size and how far it will seat. The test rings only took ~8 min to print.
The wall thickness is also adjustable, and I used 1.6mm. In Cura I set line-width of 0.4mm and wall thickness of 0.8mm. This way there is just and outer and inner wall (no infill). I find that Cura at least doesn't use nice continuous line between the inner and outer walls (fills the space with lots of small lines instead of nice continuous circular lines). If you want it thicker, I would suggest adjusting the wall thickness setting to avoid this (e.g. to make a 2.4mm thick adapter, adjust the wall in the CadQuery file to 2.4 and then use a wall thickness of 1.2mm in Cura).
If you want to try CadQuery, I think FreeCAD is the easiest way. Once you have FreeCAD installed, you should be able to install CadQuery inside FreeCAD through their built in addon manager.
If you don't want to mess with CadQuery or FreeCAD, if you leave a comment or message me, I can make and upload a different sized stl file.