I made the single-curve nightstands in the photos above, but the same steps I've used here, including many rules of thumb and limitations I discovered along the way, could easily be applied to a wide range of bent ply pieces and parts. Once you've made the molds the nightstands are easy, so this is a great project for designs with lots of self-similar parts, too.
You can check out more and larger images of the finished product on my website. http://www.phil-seaton.com/ Click "NightStand" once you get there.
Step 1: Tools and materials
In addition to some everyday items, such as a paint roller & tray, quart-size mixing container, sandpaper, etc, a few special items are needed:
Glue: I recommend DAP Weldwood Plastic Resin Glue. It comes in a powder form and mixes easily with water; it cures chemically to an ultra-hard brittle glue with absolutely no give. This is important, as the layers must not be allowed to flex next to each other to maintain the curves. Also, the chemical cure helps to make sure the glue in the middle, far from any air, still cures completely.
Particle Board / MDF: Your mold will need to be made solid, so be sure to purchase enough for both sides of your mold, including at least 2-3" beyond your actual piece. I highly recommend assuming that the two halves of the mold will come out of a rectangular area, as the parallel outside edges will need to be clamped to each other. For this project, I used exactly a full sheet of 3/4" Particle Board.
Veneers: There are several factors to consider when choosing veneer for your project. 1) The look you want on your final piece 2) The tightest curve you're planning to bend (I recommend bending a small piece around the tightest curve in your mold to make sure it doesn't snap) 3) The number of layers you'll need given the veneer's thickness and 4) The type and thickness of your interior veneers (which aren't as visible as the surface veneers).
Veneer Tape & Roller (+ a spare sponge): Veneer tape is special stuff that shrinks as it dries, closing gaps that may have been present in your veneers before taping the edges together. Chances are very slim you'll have veneers the right size & shape for your project, so you'll need this to make large enough continuous sheets. You apply water to one side (like a stamp), and then roll it on with a hard wood roller.
Dowels & matching drill bit: You'll need these to align the slices of the mold as they're cut, and also to stack them all once they're done. You'll need at least 3 dowels per side of your mold, and it helps if they're all in once piece. So if your piece is 2' wide and you can only get 3' dowels, I'd recommend buying at least six. Get a spade bit to match; 3/4" or 7/8" for dowels and spade.
Flush-trim Bit: Once you've got one slice of your mold perfect, you'll be using a flush-trim router bit to make the others exactly the same. Get a good beefy one, but make sure it fits your router. I found a bottom-bearing bit to be easiest for the setup, but you should be able to make it work with a top-bearing bit also if that's all you can find.
2x4's (qty 2 or 3) for clamping cauls (if you make these curved cauls they can save you some clamps, but they're not totally necessary)
Stop and reconsider if you don't have, or don't want to buy, the following tools which can be found in most well-equipped shops:
- Table saw. A nice heavy one is always best, but even a contractor's saw should do for this
- Band Saw. For rough-cutting mold slices
- Router. For flush-trimming mold slices
- Heavy clamps (you'll always need more than you think. Make sure you have some long enough to go around the longest end of your mold.
- Drill press (it's critical that the holes you drill for registration of mold slices be drilled straight!