This project took a while, but it was worth it. It measures the height of an athlete's vertical, much like the standard 'Vertec' system (link below), but it was made less expensive to make. Included here are the 3d prints, but you'll need other objects to complete the build. I didn't provide plans for the base, as that was just improvised in the wood shop.

Parts required (all easily found at Home Depot):
-2" PVP pipe
-1/2" PVP pipe
-Wood for base
-Dowel (thick for inside the PVC, thin to hold a weight plate)
-Weight plate (I used 10 pounds)
-Bolts, washers, and wingnuts

Some notes:

• Each 'vane' is 1/2" high. The washer is another 1/2" tall.
• The brackets are adjustable, so that kids of all ages can use the system. I used basic bolts and wing-nuts to tighten them.
  -The brace is done in a T-Shape so that athletes don't hit their toes as they run. There is a hole cut to the exact diameter of the 2" pipe.
  -There is an additional dowel coming out of the base (not shown) that goes up 4 feet within the pole for extra support.
  -The dowel at the back of the 'T' is to hold a weight. This just helps counter-balance it.
  -The main stand is 2" diameter PVC conduit piping.
  -The rod holding the vanes is 1/2" PVC piping.
  -I've left the pipe longer and added more vanes above the top, because it is 10" high, and some of my students can jump higher than 10 feet.
  -I printed 24 vanes and washers so there are 2ft of jump-testing difference.
  -The colours of filament are alternated so it's easier to see how high an athlete jumps.
  -I've added "+1" on the first vane, "+2" on the second, and so on using acrylic markers. This makes it easy to calculate how high the students jump.

This design has been hit thousands of times and shown no signs of damage. If you build it, make sure that the base is heavy enough that it won't fall over, that there is a dowel supporting the pole, and that your 2" PVC really wedges into the support hole.

I'm not going to iterate this, but if I did, I'd bevel the corners so if a kid jumps and hits it, it won't be sharp. I would also make TPU donuts that wrap around the internal dowel. But it doesn't feel necessary at this point, so I'll leave it.

Kids love it. It's a permanent setup in my class, and it's used all the time.