Mark,
I tried making one from PVC fittings like some of the YouTube videos show. It worked just enough to make me realize that I really need one of these. Then it failed, then leaked and made a mess. So, I started to search for a proper solution. There is a pro one that is over $1000 that is nice, but a bit unnecessary for me. I ended up with one off of Amazon that is made from automotive paint gun parts. It was around $120 but quite easy to use and setup. It came with everything you needed. I had a slight issue with the heater coil, and they sent me out a full replacement element at no charge. This unit helped me chase down many small vacuum/boost leaks on my son's WRX. I also ordered an additional item that I will link below
Here is a link to the smoke machine:
https://amzn.to/3KOZRga
I also ordered one of these to better block off the intake pipe while giving me a port to plug the smoke machine into. I was using plasic lids and tape but found it would leak smoke and make it more difficult to see where it was coming from.
https://amzn.to/44dujr3