The super gold sucker is very easy to build. You just cut you 3" barrel whatever length you want. Cut the plunger piece of 1" the same size. You need a 3" schedule 40 45 degree elbow, a 3" schedule 40 slip pipe cap, a 1" schedule 40 slip pvc 90, coupling and pipe cap. You also need a schedule 3/4" schedule 40 pvc slip pipe plug. You also need a 3" plumbers test plug, the kind with 3 ridges and wing nut.
Fro the handle, I cut 2 1 1/2" pieces of 1" pvc and glue the 90, coupling and 1" pipe plug together. You cut a hole with a 1" hole saw(1 3/8") in the center of the 3" pipe cap. You drill a 3/8" hole in the 3/4" pipe plug. Most of the time, you have to heat the 3/4" pipe plug gently until it is slightly pliable, then tap it into one end of the 1" plunger piece. After it is cooled down, you take it out and put a 2" x 3/8" tap bolt through from the inside, and then take apart the the 3" test plug. You will have to trim the larger washer to the size of the smaller washer. Then bolt on one of the washers onto the bolt sticking out of the pipe plug. I use stainless steel bolts and nuts. After you have bolted the washer on, you can glue the pipe plug onto one end of the plunger shaft. Then you slip the 3" pipe cap over the shaft and you can glue the handle on the other end. This completes the plunger.
For the barrel, you just glue on the 3" 45 degree elbow on one end. I also drill 4 vent holes down about 2 1/4" from the other end barrel. They serve 2 purposes, one to vent back pressure, and 2, if you don't have them, eventually you will lay down the super sucker, and when you pull back on the plunger, you will get a face full of water.
For the 3" nozzle, I just cut a 6" piece of 3 ". Do not glue it one, it gets a lot of wear!!
Sorry for the long explanation, but I don't have any pics showing the seal on the plunger.
Here is a link that shows some more pics .
3 inch Hand Dredge Super Gold Sucker 30" Barrel Gold Mining Prospecting Tool | eBay