I designed this so that the ventilation pipes for a ShopBot Desktop could fit over the end pieces but they are standard 2.25in pipes (inner diameter). There are 3 parts to print;
1.) Y splitter: the main part (print one per set)
2.)Y adapter: the smaller tube which is used to create a channel to fit the stopper into (must print one each of the 3 openings). The tabs on the end are used for lining up the pieces, I'd recommend superglue.
3.) Y closer: the flat piece that closes off each pipe after the other two parts have been connected (print 3 for each opening).

Since this is an important piece I wouldn't recommend anything less than 50% infill, 75% in good and 100% is best case scenario. Supports 100% needed for every print, no acceptations. As well I always add the SolidWorks file if possible, I have had trouble opening these from thingaverse but I believe it's only because I have an only version.

In order to fit the print onto my Makerbot Replicator + I had to split the print in half so I made a shorter version (Y splitter sm) the slit into a left and right model which will be connected after the print and all other parts will be the same.

Yes

75%