Step 1: Materials and Tools
1) The TORD file cabinet base: This isn't really a table -- it's the base for a file cabinet. I scored one in my local IKEA's as-is room for $9.99.
2) Slate (or some other stone of your choosing): Slate is available from your local big box home store for about $1.00 USD per 12" square tile. I used six of these tiles.
3) Plywood: Underneath the slate is a piece of plywood roughly 21" x 27" x 5/8". For this table the smallest "handy panel" size will do. I suggest you use the lowest grade plywood you can find. MDF might work in a pinch, but the weight of the stone top may cause MDF to sag over time.
Tools required to build this table
1) A circular saw, table saw, jig saw, or any other saw capable of cutting plywood. As we'll see in Step 3, you may not need this.
2) A tile saw, jigsaw (with carbide grit blade), circular saw (with diamond blade), hacksaw, or any other saw capable of cutting stone. As we'll see in step 4, this may not be required.
3) A chisel, file, or Dremel. This is needed to make small notches in the plywood backer in Step 3.
Step 2: The TORE File Base
Step 3: The Plywood Slate Backer
Cut a piece of plywood that fits inside the frame. Your frame may not be perfectly square, so take careful measurements and make careful cuts. Barring the use of a table saw, the easiest and most effective way to accurately cut plywood is with a circular saw. A jigsaw can be used, but it's hard to get straight cuts with a jigsaw.
Big box home stores might be able to cut the plywood to your specifications for a nominal fee. This would probably be the way to go if you lack the tools or desire to do it yourself.
Once you're finished cutting the base, there's the optional (but recommended) step of cutting notches so that the wooden backer rests flush on the file base's metal tabs, and not on the welds of the metal tabs. The picture below illustrates this step.
Mark the location of the welds and cut away a small amount of the wooden backer to accomodate them. You can use a chisel, file, or dremel for this.
You can choose to seal or paint the wooden backer if you like. It's not necessary, however.
Step 4: Laying Out and Cutting Slate
If you do end up needing to cut the slate, here are some options:
1) Have somebody else do it. I'm pretty sure that the big box home stores will cut stone if you ask them to. The downside here is that you have to deal with an employee of a big box home store.
2) Dry cut the stone with a diamond blade in a circular saw, or a bicarbonate blade in a jigsaw, or with a hacksaw. Note that it will be difficult to get a straight cut with a jigsaw or hacksaw. This is probably the least preferable method especially in light of this WARNING: If you dry cut stone you MUST NOT inhale the dust created by cutting (and, by God, there's going to be a lot of dust). Dry cut stone outside with appropriate lung protection.
3) Wet cut the stone. This is the route I chose. I used one of those cheapo table mounted tile saws. I don't recommend that you buy one (I didn't). Instead, find a friend who has done some kitchen or bathroom remodeling and borrow theirs. You might have to ask a friend of a friend, but somebody will have one, because everybody on Earth is separated from a tile saw by at most six degrees of separation. Wet cutting the stone makes a big muddy mess, but there's no airborne dust.
When you're done cutting your stone, wash it thoroughly and give it some time to dry out.
Step 5: Putting It All Together
Options And Upgrades
Sealing or painting the wooden base: After six months of use, it turns out that this isn't really necessary.
Mounting the tiles: If you enjoy making life hard on yourself you can mount and grout the tiles. In my opinion, if you were careful with your cuts, this isn't necessary. I've been using my modified table for six months and the tiles have stayed pretty much where I put them. Also, it's turned out to be advantageous to remove the tiles for washing.
Step 6: Errata and Updates
Updates: I called around and found that the TORE file base has been discontinued. Doh! I did, however, peruse IKEA's floor displays in an attempt to find a replacement. Here are some candidates for slatification:
RAMVIK: It appears that the glass top can be replaced by thin gauge slate.
EKERSBY: The top of this table can be slatified, possibly requiring the addition of rails.
Neither of these is as perfect as the TORE was, however. I promise to keep my eyes out for a store-purchasable replacement.