I wanted a short laptop desk that we could keep in the living room and that would allow reasonably comfortable use of the laptop while sitting on the sofa. Previously, the kids had been using the laptop while sitting on the cushion of an Ikea Poang ottoman on the floor and with the laptop resting on the ottoman's wooden frame--not ideal. We were at Ikea buying a dining room table, and they had the famous Lack side tables for $5 each (here are other things people have done with them--the Lack seems to be the most popular side table for hacking). I bought two, assembled one, and experimented for a few days to find the right height for the laptop table. A single Lack table was too low. A Lack table with a Settlers of Catan box on top of it for the laptop to sit on was too high. The best height compromise was a Lack table with a second tabletop on top of it, from the other Lack table. But it would look silly to have a laptop table with a double-thickness top, plus more storage is always useful.

So out of the two Lack tables, I cobbled together one, approximately the height of the double-top table, with ample storage space. One can think of this as a remix of this Instructable (but to be honest, I saw it after I did my project).

Unfortunately, I didn't take in-process photos, but I'll try to explain things step-by-step anyway, using some staged photos and some photos of the final product.

Unity of visual style is provided by taking the width of the Lack leg, which is the same as the thickness of the top, as the unit of measurement.

Ingredients:

Two Lack side tables.
Four wood screws, about 3/4" longer than a Lack leg-width.
Wood glue (Titebond III).

Update [November, 2015]:

Unfortunately, the leg attachments on the Lack haven't been very strong -- I don't know if this is because of the original structure or my modifications. As a result, two or three I've had a leg of the table get bent out of position, due to the table being moved around.

I ended up adding metal angle brackets to a leg, to keep it more steadily attached to the lower tabletop, the first time this happened.

The problem seems to be that legs are attached by large double-ended screws that go into OSB filler inside the legs and the tabletop, and eventually rip out of the OSB. The last time I had a leg get loose, I ripped the OSB filler out of it, and instead fabricated a cube of softwood that would sit inside the leg. I attached the cube to the underside of the tabletop, with a combination of glue and the screw, and then glued it inside the leg (the dimensions were designed to fit inside the leg). Sorry, no photos.

Step 1: Legs and Posts

Take a Lack leg. Cut a segment at one end two leg-widths in length. (If you're using a saw with a wide kerf--I used a miter saw--then make sure that the kerf goes on the long side of the cut, so the short segment is as close as possible to two leg-widths.)

Be careful cutting. Apart from MDF blocks at the two ends, the legs are hollow.

Repeat with three other legs. You will now have four shorter legs, and four short segments. Make all the legs as close to the same length as possible, e.g., by setting a stop on a table or miter saw.

Step 2: Put Wood Inserts in Legs

The legs are hollow inside. Shake out the sawdust, and cut wooden block inserts (3/4" softwood is what I used) to fit the hollow ends at the cut. You will need eight inserts cut and (if necessary) sanded to size. Glue them into the hollow ends, making sure that the inserts are as flush as you can make them with the outsides of the legs. (I pressed them against a concrete floor to ensure flushness.) Wipe off excess glue.

Step 3: Attach Segments to Tabletops

The four short leg segments have the MDF with predrilled holes on one side. Attach that side to the underside of one tabletop with the standard two-sided Ikea Lack leg attachment screws, and do this for all four short segments. Make sure that the segments are all screwed in equally hard.

You now have a super-short Lack table! Place it upside down, with the "legs" (i.e., the short segments) sticking up. At the bottom (or top, when upside down) of each vertical segment you will have the wooden block you glued in.

Drill holes all the way through the second tabletop, about 1/2" or 3/4" diagonally away (e.g., towards the center of the tabletop) from the leg attachment holes. Put this tabletop upside down on top of the vertical segments from the first tabletop and align the tabletops carefully. Now, continue one of the holes you just drilled into the wooden block in the segment that is now under it, while keeping the tabletops aligned. Enlarge the top end of the hole to countersink your wood screw. Now run a wood screw through what you just drilled. This will connect the second tabletop (which will eventually form the shelf) to the short segment that is connected to the first.

Realign the tabletops with the first screw in place, and repeat for the other three corners.

You now have two tabletops with short segments between them.

Step 4: Complete the Legs

You still have four legs that were shortened by removing the vertical segments from them. They have MDF blocks on one side, with Ikea's predrilled holes, and your wooden inserts on the other. Connect the MDF block side to the tabletop with Ikea's two-sided screws and, optionally, some glue (I put Gorilla glue both on the wood near the screw and on the screw itself in the end--I found that the legs weren't quite strongly enough attached with the two-sided screws).

If you're putting it on a wooden floor, I recommend putting felt pads on the other side of the legs (the one with the wooden inserts).

If you like, you can say you're done now. The resulting table with a shelf has an elegant Ikea-like look. (You can also make it a bit taller by using the uncut legs instead of the cut ones.)

However, because the shelf has no edges, stuff you put on the shelf can slide out. Moreover, any mess on the shelf is visible. For that, there is one more step.

Step 5: Raised Edges

I added raised edges to the by cutting the remaining four Lack legs to fill the space between the vertical supports on three of the four sides of the table.

For the sake of symmetry, on the back side I cut approximately equal-size segments from two different Lack legs to fill the gap, and I glued them in with wood glue. On the left and right sides, I used one full leg each, which didn't quite fill the gap, plus a short segment, arranged symmetrically.

If you used the full-length legs in the previous step, you may only be able to put raised edges on one or two sides.