I distinguish 3 groups of parts in terms of printing.

The first group would be the parts you can print in PLA, PETG or other hard plastics and have "screw" features, these ones are the body, the top cup, the bottom cup and the spring holder head. They must be printed in 0.1 mm layer height so the "screws" really work.

The second group would be the rest of hard plastic parts, which can be printed in 0.2 mm layer height.

Finally the third group would be the TPU parts. As all of them are small, I would recommend to print them in 0.1mm layer height, specially the piston part.

The longer the spring, the harder it will be to print the top part... I can print them more accurate in PLA than in PETG, as this second one is more flexible. 

How you print them is very important... All solid, change your perimeter thickness between 0.35 to 0.4 or 0.48 for the best fit and full fill of every wall in each part. If you want real vacum for your oil, use o-ring instead of bottom seal and screw quite hard the top cup with the proper TPU seal.

In terms of performance, these shocks will be obviously under the cheap sourced ones but I think you will be surprised if you give them a try ;)