Here's a quick run through of a little skimmer I'm building for my temperate SW system. Apart from the needle wheel pump it cost about $75 to build and is comparable to a $1700 unit. Here are the two main tools I'll use (always wear proper eye protection): A "Dremel" type rotary tool with a cut off disc and a barrel sanding attachment to work the water bottle and a compound mitre saw for cutting PVC piping
I begin by marking and cutting a 5G. water bottle.
This shot shows how I've cut at a spot that leaves an extended flange on the bottle
Here's a shot of the Sedra 9000 needle wheel pump (off of the $1700 skimmer). I will be using the pump in a recirculating mode on the skimmer. It came with 1/2 of the unions glued in place and I couldn't find a reasonably priced replacement.
So I cut the collars off. Notice the 1/2" PVC pipe that fits snugly inside the pump lines.
I lined the intake and outlet of the pump up against the water bottle, marked, and then cut out holes for the bulkheads. I cut the rough holes with the cut off disc and smoothed things out with the sanding barrel.
Here are the installed bulkheads for the pump