This is a vacuum hose attachment adapter for adapting between 1 1/4" OD port to 1 1/2" ID ports.
This can accommodate any mix or match of 1 1/4" OD and 1 1/2" ID attachments.
In the images above, you will see two 1 1/4" OD hoses attached together, and a 1 1/4" OD hose attached to a 1 1/2" ID hose.
0.5mm (or as high as your nozzle allows)
100% (but you can go down to 23%)
A very easy print - no retraction, and you can print at ludicrously high layer heights.
I printed this in PLA, but any plastic should be suitable.