Plastic totes come in many brands and sizes. The following are a few that I've used with RDWC, DWC, and F&D Tote builds. I've also found a few measuring and hole alignment shortcuts along the way.
Commander 5 Gallon Square Tote (Blowes)
I'm changing the buckets in my UC RDWC from 4 Gallon Square "Letica" brand (ULINE) to these 5 Gallon Commander Square Totes (Blowes). Although I like the Letica for the sealed black lids, the walls flex more easily, which can cause the bucket to bow on bulkhead fittings especially late in the run as the buckets fill up with roots and there's more "stress" put on them. The idea is to cut holes in the lids for the net pots, then paint them black using this technique: Spray Paint on Plastic.
Top of the lid, which is set in place on the bucket. You could measure it and find the center for each lid, which can take time if you want to try and line it up as perfect as possible.
Underside of lid, flipped over. The drill bit is pointing to a mark that was left from the production mold the manufacturer used. It is perfectly dead center.
Drill a hole using a drill bit that's a little smaller than the size of the pilot bit on your hole saw. It's handy to have two drills here, or if you are only using one, then make all of your small holes on the lids first, then proceed with the hole saw drilling.
Flip the lid over and set back into place.
Notice that the hole saw's pilot bit doesn't protrude past the hole saw very much, making it very difficult to line up, even if you lean your head and look from the side. Even with a marked dot, once the drill starts rotating, it can slide off the original mark very easily causing a misalignment. The little hole is to guide the pilot bit right into place without this hassle.
Push the hole saw pilot bit into the hole. Using the square pattern on the lid as a grid, check one last time to see if everything looks lined up. A 6 inch hole saw should be "within a square" with the edges running almost perfectly tangent to the circle. With the drill set on reverse, press downward on the drill and pull the trigger a little bit at a time until you feel it groove the plastic. Then hold on the trigger and push down. If your drill has a side handle for leverage, use it. It takes some pressure and should cut through in less than 10 seconds. The backwards rotation helps make clean cuts with minimal burrs and also helps prevent cracking. If you can't get it to go through, then set the drill on forward, burst the trigger a few times for the teeth to cut a bit more into the plastic, then switch to reverse and finish the cut.
Notice how the hole is cut clean with minimal burrs. Scrape off any excess material into the bucket with a safety blade or pipe cutting tool, being careful not to gouge the plastic. Also notice how the hole is perfectly "within a square" with the edges of the square almost touching the circle. Replace with the next lid to be cut on the same bucket to collect the
waste material from each lid for easy dump and disposal.
All plastic totes are produced using a mold of some sort which will leave similar mold marks for guidance. Often times you can just use the marks as-is to drill holes, but sometimes you'll want different spacing. You can also use the mold marks as reference points for measuring and alignment to make your own marks.
Letica 4 Gallon Square Bucket (ULINE)
You can make the small guide hole on the top of the lid since the mold mark is visible without having to flip the lid over to the underside.
Hefty 10 Gallon Tote (Blowes)
See the circle with a dot in the middle? This is a slick shiny plastic so it's hard to get a pic without a reflection even without flash. You can see it much better in real life.
I marked the circles with a Sharpie for better visibility on the pic, but this shouldn't be necessary. The circles are almost exactly the same size as a 1-3/8 inch hole saw, which happens to be the exact size for standard F&D fittings. This spacing allows for 8 half gallon square nursery pots, 4 on the top row, 4 on the bottom. Larger pots may need different spacing. Stacking this onto a Hefty 18 Gallon Tote will make an excellent F&D Tote based on @HydroRed's original design: HydroRed's DIY Budget Flood & Drain.
TIP: pull off a handle on the side that the water pump power cable comes out of to expose a groove that allows for the cable to fit flush with the buckets.
...it's like these totes were made for building F&D Totes
Sterlite 10 Gallon Tote (Walmart)
Same concept applies, harder to see, but below is a closeup
The darker dots are dead center for standard F&D fitting holes
These Sterlite 10 gallon totes fit into Sterlite 18 gallon or 27 gallon totes (Hefty currently has 18 gallon as their biggest tote). The larger capacity is nice, but you give up some head space because they are taller. However, if you have a higher ceiling and want to fill up your totes less often, then this is a great option to have.
Any holes on the sides of the totes will need to be measured accordingly, as there are no mold marks to use as a reference. Silver Sharpies are handy to have to mark black totes. Framing squares and yardsticks also help to make straight lines.
Commander 5 Gallon Square Tote (Blowes)
I'm changing the buckets in my UC RDWC from 4 Gallon Square "Letica" brand (ULINE) to these 5 Gallon Commander Square Totes (Blowes). Although I like the Letica for the sealed black lids, the walls flex more easily, which can cause the bucket to bow on bulkhead fittings especially late in the run as the buckets fill up with roots and there's more "stress" put on them. The idea is to cut holes in the lids for the net pots, then paint them black using this technique: Spray Paint on Plastic.
Top of the lid, which is set in place on the bucket. You could measure it and find the center for each lid, which can take time if you want to try and line it up as perfect as possible.
Underside of lid, flipped over. The drill bit is pointing to a mark that was left from the production mold the manufacturer used. It is perfectly dead center.
Drill a hole using a drill bit that's a little smaller than the size of the pilot bit on your hole saw. It's handy to have two drills here, or if you are only using one, then make all of your small holes on the lids first, then proceed with the hole saw drilling.
Flip the lid over and set back into place.
Notice that the hole saw's pilot bit doesn't protrude past the hole saw very much, making it very difficult to line up, even if you lean your head and look from the side. Even with a marked dot, once the drill starts rotating, it can slide off the original mark very easily causing a misalignment. The little hole is to guide the pilot bit right into place without this hassle.
Push the hole saw pilot bit into the hole. Using the square pattern on the lid as a grid, check one last time to see if everything looks lined up. A 6 inch hole saw should be "within a square" with the edges running almost perfectly tangent to the circle. With the drill set on reverse, press downward on the drill and pull the trigger a little bit at a time until you feel it groove the plastic. Then hold on the trigger and push down. If your drill has a side handle for leverage, use it. It takes some pressure and should cut through in less than 10 seconds. The backwards rotation helps make clean cuts with minimal burrs and also helps prevent cracking. If you can't get it to go through, then set the drill on forward, burst the trigger a few times for the teeth to cut a bit more into the plastic, then switch to reverse and finish the cut.
Notice how the hole is cut clean with minimal burrs. Scrape off any excess material into the bucket with a safety blade or pipe cutting tool, being careful not to gouge the plastic. Also notice how the hole is perfectly "within a square" with the edges of the square almost touching the circle. Replace with the next lid to be cut on the same bucket to collect the
waste material from each lid for easy dump and disposal.
All plastic totes are produced using a mold of some sort which will leave similar mold marks for guidance. Often times you can just use the marks as-is to drill holes, but sometimes you'll want different spacing. You can also use the mold marks as reference points for measuring and alignment to make your own marks.
Letica 4 Gallon Square Bucket (ULINE)
You can make the small guide hole on the top of the lid since the mold mark is visible without having to flip the lid over to the underside.
Hefty 10 Gallon Tote (Blowes)
See the circle with a dot in the middle? This is a slick shiny plastic so it's hard to get a pic without a reflection even without flash. You can see it much better in real life.
I marked the circles with a Sharpie for better visibility on the pic, but this shouldn't be necessary. The circles are almost exactly the same size as a 1-3/8 inch hole saw, which happens to be the exact size for standard F&D fittings. This spacing allows for 8 half gallon square nursery pots, 4 on the top row, 4 on the bottom. Larger pots may need different spacing. Stacking this onto a Hefty 18 Gallon Tote will make an excellent F&D Tote based on @HydroRed's original design: HydroRed's DIY Budget Flood & Drain.
TIP: pull off a handle on the side that the water pump power cable comes out of to expose a groove that allows for the cable to fit flush with the buckets.
...it's like these totes were made for building F&D Totes
Sterlite 10 Gallon Tote (Walmart)
Same concept applies, harder to see, but below is a closeup
The darker dots are dead center for standard F&D fitting holes
These Sterlite 10 gallon totes fit into Sterlite 18 gallon or 27 gallon totes (Hefty currently has 18 gallon as their biggest tote). The larger capacity is nice, but you give up some head space because they are taller. However, if you have a higher ceiling and want to fill up your totes less often, then this is a great option to have.
Any holes on the sides of the totes will need to be measured accordingly, as there are no mold marks to use as a reference. Silver Sharpies are handy to have to mark black totes. Framing squares and yardsticks also help to make straight lines.