This is so simple to make all you need is:
2- 10ft sticks of 3/4" PVC Pipe
1- 3/4" PVC End Cap
1- 3/4" PVC Coupling
1- PVC Hose Connector
PVC All Purpose Glue
10-15 Zip Ties
Drill with 1/8" drill bit
PVC Cutting Tool/Saw
You need to connect and glue the 2 long PVC sticks with the coupling. On one end glue on the PVC Hose Connector. From here, find the best place that is closest to the water hose so that you aren't connecting the hose in an awkward area. You will zip tie the hose connector and PVC pipe to the trampoline at that spot. Then move around about 4 ft and put another zip tie there, and so on until you get to the end. Once you have gone around the whole tramp and secured it with zip ties you should be back to the hose connector. Cut the pipe and glue the end cap on here. Next, take the drill and drill holes slightly slanted to the center of the tramp every 2-3 feet. The closer the holes are the lower it will spray, the farther apart the hole the higher the water will spray. Make sure the glue is dry before you turn on the hose. Have fun and always supervise kids when they are jumping on a trampoline and are around water.
Happy Summer!!