Basically I wanted something cheap and big. After looking around Bunnings I found some cheap pine in various widths that is 19mm thick. It'll do the job but it's full of knots and you'd be hard pressed to find a straight piece of wood, but we can deal with this.
The design I'm going to use is pretty simple, front, back, two sides, and a base. The sides slot into dados in the front and back and the base fits into a routed channel at the bottom. Then it's all glued and screwed together. Below are a few pictures of a drawer.
|All the pieces ready for assembly|
|Dado for the side and routed groove for the base|
|Close up of the corner|
|Routed stopped dado in the front panel|
|A knot in the wood glued and filled to stabilise it|
|The side fitted to the front|
|The drawer assembled with a notch chiselled out for the drawer slides|
|Drawer slide attached|
|Drawer slide extended, clearing the cut-out|
Most of the problems with warped wood are taken care off when it is assembled. The sides are straightened when they slot into the tight dadoes, and the front is pulled straight when it's screwed to the sides. It's not completely straight, but it's close.
The base is 7mm thick ply and seems to be sturdy enough. I loaded it up with 50 kg of text books and it held all right. Initially I planned to use cheap drawer runners but they were terrible and and too unstable. They might be OK for smaller drawers, but for something 2 by 3 feet they are useless. I settled on full extension drawer runners from Hafele. They are smooth and work beautifully. www.elraco.com.au had them at a decent price, and I wish I could have bought more just to get the price break at 10 units.
It's all still a work in process, but I'll post more when I'm done.