I figured out that a 1m pipe is too short, 2m is good but not handy so I chose 1,5m.
Use the glue like it's describe on the instruction for the first plug. Fill the pipe half with water. Close the second end with the second plug and glue.
(You also can experiment with the amount of water you use but be careful if you don't want to glue the plugs the water might push it out)
Done. Slashpipe/Powertube for 20$ instead of 200$ ;-)