Same problem for me. How much does a Rex grigg 3" reactor cost to make? Do you have a video example or of sort, I've never really understood diy reactors
How much are you looking to spend on one? It may be better to buy one from nilocg instead of doing DIY if you're not familiar with everything.
The cost of the diy one depends largely on the tools you already have and the features you want to have on it.
If starting with no tools a standard original rex grigg reactor that is outlined here rex grigg reactor
probably going to run you $35.
A 3" version with all of the reducer fittings and extras to get you down to 3/4" fittings in and out will probably run you $50
and a 3" one the same as above with a bypass will likely run you $60-65.
If you want to run a brass 3/16" fitting for the Co2 line include about $10 for the fittings needed
All of these are just ballpark numbers it may be more it may be less, and it includes the fittings, pipe, pipe cement, teflon tape for the screw fittings, and a pipe cutter. Depending on what you have and don't have already changes the price somewhat.
For a prebuilt rex grigg reactor from nilocg it runs $70, cerges runs $75, and rex grigg with a bypass $95. Yeah it's a premium, but if you have to buy everything from scratch it might not be that far off from the price of the all the parts needed when all said and done + it's built for you.