Shell and Tube Heat Exchanger Pen Holder

I wanted to design something that would be a fun tip of the hat towards chemical engineers.

This desktop pen/pencil/whatever holder has 14mm diameter holes to fit all sorts of desktop supplies (though I recommend not trying to store paperclips, or heat exchanging fluid).

I suggest printing the tube section with the holes facing down and without support. The shell portion definitely need support, though this will add significant time. I printed the tubes at 60 mm/s and the shell portion at