Buy some acrylic......buy the weldon (#4 and #16 if you can afford it and find it) then play around with some small pieces.
You will get the hang of it.
I like to use vice's to secure the parts to be joined in the right position. Then I go along the seam with a syringe and a non sharp needle squirting weldon #4 as I go.
I let it sit for a hour or two and then it's pretty stong.
Most of the stuff I make doesn't need to be water tight though.