Here, then (on DropBox) are Start, Finish and gate 2, 3, 4 and 5 arches, designed using TinkerCAD, available as downloadable (free) STL files for your delectation and delight. On my Robox they take about 2 hours each in the lowest resolution, and about 3 if you want something a little less visibly ‘layered’: personally I don’t mind the look as is. They’re deliberately designed to be pretty foolproof to print, and as such have no detail on the back.
If you want me to print a set for you, please get in touch. A complete set at the lower res is £15 plus postage, Start/Finish and gates 2,3 (enough for a standard Death match) is £10. (Costs reflect time spent designing and the time they tie up my printer for.)