You can buy PETG on amazon or Performance PC both are great vendors You can use anything heat resistant and round for a bender like a soup can or a wooden dowel if you feel you need a jig and aren't to handy as to make one yourself you can buy one from PPC. For fittings be careful you need the correct fittings not just for the size of the tube but the right fittings for the tubes themselves some will not work with each other due to manufacturing. That is the tube might say 3/8 x 1/2 but the outer is a little less causing it to leak with incorrect fittings. PETG comes normally in 3/8 x 1/2 but you can get it slightly larger at 1/2 x 5/8. The size difference is mostly for looks and won't effect performance much. I use Monsoon tubing and fittings but PrimoChill also makes nice fittings and PETG tubing. Lastly, despite PETG being all the rage acrylic is just fine for most builds; it is not semi-flexible like PETG but the brittleness is exaggerated and it is also a good choice. Good Luck
EK also has some, and if you really want to hurt your brain and budget there is borosilcate glass tubing out as well, i think mayhem did a video on it https://www.youtube.com/watch?v=qfLdwHGentA