The default print orientation is for each piece to lay on its side(see first image) and all three sections are designed to be arranged on the print bed as show which will fit on a 200mm x 200mm build plate. If you have a smaller bed, or prefer to print one section at a time, you will find that the additional files contain just the named section of pipe(Left, Right, Center) but should also be printed laying down as pictured. This orientation allows printing without supports, but a raft is advisable, as I have had some issues with corners lifting(likely due to the very sharp corners at extreme edges of my print bed). Another advantage is that the layer lines will be vertical when the piece is used in its normal orientation, which will allow for a much smoother ride for the fingerboard. Though the object is solid and has large faces, but it should print just fine with a very low infill percentage, as long as you make sure to solid fill a few extra top and bottom layers, which will also help with rigidity while in use. Additionally I would recommend using several shell layers which will help the top curve of the drop in ramps, and ensure that all the ramp faces remain rigid.
For post processing, just align them and super glue, or head weld the peices together, then lightly sand the seams where they meet to ensure a smooth riding surface.
Estimated time and material to print a single section: 7 hours at 70 grams*
Estimated time and material to print complete 6 section halfpipe: 42 hours at 420 grams*
Approx. size of each section is: 120mm x 130mm x 90mm
*Time and material estimates based on a print speed of 100mm per second, infill at 10%, Top/Bottom/Shell thickness at 1.2mm, a .4 nozzle at .1mm layer height, and no adhesion or support options on.