For this project, you will need:
Two food grade 55 gallon barrels, one MUST be whole, bottom 12" must be intact (at least) on second barrel
a box of 1/4" by (1/2" long)Stainless steel carriage bolts (MUST BE STAINLESS STEEL) You wont need them all, but a box of 100 runs us under $8 at Ace Hardware (Try to support the little guy!).
A box of 100 staineless steel washers (about $3 to $4)
A box of stainless steel 1/4" nuts (under $7)
A piece of plexiglass (can be 1/8" the thin, cheap stuff) Ours was from scraps.
aquarium safe clear silicon (two tubes, it can probably be done with one, but get 2 just to be safe)
a small pond pump (we use 400 GPH pumps for our systems)
either a 10 foot stick of 1/2" PVC, or some scraps and fittings
two 1/2" PVC male adapters (slip to thread)
Two 1/2" PVC female adapters (also slip to thread)
A 3/4" TAP to thread a couple holes
a 3/4" hole saw and electric drill
A jig saw
A Sharpie (to mark out your cuts on the barrel)
some expanded clay or gravel (media)
A 12" piece of 4" PVC as a media guard
PVC cutters, or a way to cut PVC
A bell siphon (I wont cover that here, but there are a great many resources on this site, and you tube that will show you how to build one, and there are alternatives to the bell siphon that work well too.)
a 1/2" ball valve
I think that is about it.
Remove the top of the barrel, leaving a small lip inside of the top, to help the grow bed sit comfortably and use a ruler to mark out two squares on the top third of the barrel, ours are about 8 inches by 8 inches. Use a drill, to drill a hole in a corner of the marked area you plan to cut so that you can get your jigsaw blade in. make sure to make rounded corners to help the barrel keep its integrity. Remove any burrs left over after the cut. they can be picked off by hand, or a pocket knife works well also.
Now onto the plexiglass. I have found that the easiest way to cut plexiglass is with a jigsaw, mark out your rectangle, 11" tall, by 20" long, and put masking tape on the bottom side of the glass under your planned cuts. The tape prevents the plastic from fusing back together after the saw blade passes through making the cuts.
Once you have your 11" by 20" piece of plexi, mark out your bolt holes with the sharpie. I suggest going 2" apart, leave a 1"buffer between the edge of the glass, and the bolt holes. To drill the holes, I used a 3/8" drill bit. Make sure to run your drill backwards, and apply very little to NO pressure to avoid cracking the plexiglass. Once the plexi is drilled, remove burrs around your holes, and set a pizza pan in the oven upside down, preheat the oven to 250° Place the drilled plexiglass on the pan, and heat it for 5 to 6 minutes. It will start to sag a bit at this point and be soft enough to form. Using cotton gloves, remove the plexiglass from the oven, and place into your barrel, (make sure both the glass and barrel are CLEAN) and hold it inside the barrel for a couple minutes to make sure it forms to the curve of the barrel. Leave it there for about 10 minutes to cool fully before grabbing the drill again. It is now time to drill the barrel. Using the plexglass as a template, drill the middle holes on top and bottom of the window, and insert a bolt from the inside of the barrel to the out, and add a washer and nut. Next, drill out the holes on either side of this middle bolt, (top and bottom for a total of 4 holes) and add the bolts washers and nuts to these. Continue using this method drilling from the middle out and inserting bolts as you go until you reach the edge of the window. The side holes can all be drilled one after another on both sides and then bolts can be inserted.