Since we were going to use IKEA's tub we had to base our unit off those measurements.
We started with 6 6ft 1x10 boards. He cut 4 39" boards (top and bottom) and 4 22" boards (sides) and screwed those together. This produced two boxes/frames measuring 39"x 23.5" tall.
The two boxes/frames were secured together with 1x4s on the sides - we were going for a crate type look - but you could do this on the inside of the box instead if you prefer, just make sure you leave room for the bins to slide in and out
So we have a box measuring 39" long x 23.5" tall x 18.5" deep. The tubs are ~17" deep.
The two dividers were added next. 4 22" board were cut for these and then arranged, making sure the bins still fit nicely (photo above). Those were then also screwed in place. Each space is 12" (the tubs are 11 3/4 wide at the top).
The rails that the bins slide on are remnants we had laying around from other projects. They do measure roughly 3/4x3/4 though so 1x1s from the store would work though you may need to adjust your width slightly. If your bins still don't slide freely, take to the rails with a sander ;)
12 18" rails were cut and attached using a finishing nail gun.. The top rail is 1.5" from the top and there is a space of 5 5/8" between the first and second rails. We decided not to add rails for the bottom, larger bins as they were likely to be heavy and we preferred they just rest on the bottom of the unit.
Gave it a quick sand and we were done! It might get painted one day and I think the top will become a Lego table but for now we wanted to put it to use! It took approximately 8-10 hours to build but you may or may not be able to build it faster without a 3 year old trying to help ;)
Don't be like me and not buy enough tubs! Looks like another trip to IKEA is in order. Darn.
The wood cost $48.20 (7.42 a piece) at our Home Depot. You may be able to find 1x10s cheaper, actually, I'm sure you can! Or you could buy 8ft boards instead of 6ft ones to save more per foot. I bet you could find a coupon too. If I had thought about it I would have sent him with the 10% off one I have for an additional 4.82 saved. Doh.
We already had the screws and everything else we needed. The solid wood Trofast at IKEA is 75.72 after tax. The small tubs are $3 at IKEA and the red ones are $4. You have to buy them separately either way though.
In the end we saved $27.52 after tax by building it ourselves (could have been 32.34 if we'd used our coupon!!) I also like that I know what is *on* the wood -- or rather, what isn't on it, I may give it a rub with some beeswax... AND, I didn't realize this, but there was wood leftover; if I had been out there I would have built the unit one small tub taller to add more storage and utilize the extra wood for the same price. (husband says he knows there was but he was just following my directions lol) Oh well, next time I will be sure to use my calculator properly!