2 marbles or balls, find something to plug the hole! Both need to be over 8mm in Diameter. One of the balls can be up to 1in. Though smaller the better. 2 or 1 #17 Oring. (http://www.homedepot.com/p/DANCO-17-O-Rings-10-Pack-96734/100261428) It should work without the oring just not as well :) Designed to fit onto 1/2IN ID tubing. The pump primes easily and the length of hose depends on how well of a seal you are able to make. You should be able to figure out how to put it together. Part 13 is the oring, if you have rubber type filament perhaps you can just print one.