I had some redwood fence boards sitting around, so I figured I'd start cutting some large versions of my Escher Reptiles. Only later did I realize they'd make a pretty cool table. I cut 6 semicircular segments, and I was off to the races.

Tools:

access to a CNC Router, laser cutter, waterjet cutter, or whatever will cut your material. Or a scroll saw and a ton of skill and patience.

Materials

Wood. I used some super cheapo redwood fece material. 5.5" x 3/4" x 6'. Use whatever you want. This can be adapted.
2' x '2' x 1/2" plywood square as a base.
1 Quart Glaze Coat, from Lowes
Bondo for smoothing out the sides and bottom
3 Paint colors (I used gray, gray and gray)
glue to hold the puzzle pieces down to the plywood base.

Inspiration (giving credit where credit is due...)

M.C. Escher of course.
buildyourcnc.com. This guy's videos inspired me to build my own CNC. If he can build a CNC in his living room & bathroom, I figured i can build one in my garage. The design used in the tutorial video's isn't great (not very stiff), but it's what I built, and it works. Looks like the ones he sells are much better designed than the DIY one shown in the tutorial videos.
Penny Desk.

Step 1: Cut Your Reptiles! Paint Them Too.

Using the attached 'lizard-large.dxf' you can cut out your own escher reptiles. I do it in 2 steps:

Open the .DXF file, and you'll see both and outline, and a bunch of internal lines. I do the engraving both on the internal lines, and the outline. I do it with a 90-degree V router bit. After then engraving, you can cut out the reptile with up to a 1/4" diameter router bit. A larger bit won't cut the internal radii right.

Then, I let my kids paint them however they like. Obviously, if you're using really nice wood, you'll want to skip the painting and staining steps... This would look great with 3 types of hardwood, I'm sure. Maybe I'll try that next.

lizard-border.dxf
Download

Step 2: Cut Out the Border Pieces

I cut the border pieces from the same stock that I cut the reptiles. This piece had a nice red color, which I like.

Again, g-code is attached.

lizard-large.dxf
Download

Step 3: Cut Your Table Top Base

Make your 3-axis CNC machine into a ghetto 4-axis machine.

I have 1/4-20 T-nuts embedded in my machine. By anchoring the 2' x 2' square plywood into one of the holes, I can use the CNC to cut out circles much bigger than the table could normally cut.

Pick a hole near the center of your CNC. Touch off your X & Y axes at this hole.
Drill a 1/4" hole in the center of the plywood and anchor it to the table, using a washer to help the piece turn.
move your router to X=-10.125" from the anchor point. This should give you a cut of exactly 20", assuming a 1/4" router bit or end-mill. You might want to do a test cut or three at a too-big diameter before proceeding.
Once everything's all set, lower your z-axis by your cut-depth, and carefully turn your table top.

Of course, this can be done with a router circle jig, or perhaps any number of other tools. But I like the precise and accurate adjustability of the CNC.

Step 4: Draw or Cut a Marker Circle

Draw (or engrave) a marker circle at your border inner diameter. This will give you a guide to how much glue to apply in the next step.

Mark the center so you don't apply glue, you'll need that piece out later.

Step 5: Glue in Your Reptiles

Place all the reptiles on the table to fill out the out to the guide circle you just drew. I'd suggest gluing pretty well along the edge of the guide circle, which should help keep all the reptile's limbs in place during the trim-off step about to come...

But... DONT GLUE IN THE CENTER REPTILE. You'll need access to the 1/4" hole in the plywood base for the trim off step.

Wait for the glue to cure/dry... You want everybody to stay in place during the next step.

In this case, I flattened all reptiles face down so that I end up with a flat table top. Let any un-evenness be between the reptiles and the backer plywood.

VERY IMPORTANT: I didn't fill in the seams with glue. This meant that during the finishing step, the epoxy filled in the whole space under the reptiles. This means I ended up using a full quart of epoxy on the thing -- it just kept seeping in. So... cover the seams with glue...

ALSO VERY IMPORTANT: You can see I stayed inside the outer diameter I plan to cut out next. BAD IDEA. The un-glued portion of the reptiles broke off during the trimming step. You should glue the reptiles down at least 1/4" past your outer diameter to help prevent breakage.

Step 6: Trim Off the Poor Little Guy's Heads, Feet, Tails.

Now, back to your ghetto 4-axis CNC: set your router bit so that it will cut a precicely 16.25" diameter circle. Do a test cut, check it twice. Check it twice again. 16.25" Exactly. You can cut a little large the first time -- you can always trim off more as yo need to by bringing in the X axis.

Now, start your router, and take small Z steps. Maybe 0.1" at a time. You really don't want to break stuff apart now, so go slow. Trim off all the heads, feet, and tails that fall outside the 16.25" diameter. Only trim down to the plywood -- don't go too far into the plywood.

AHHH, lots of pieces broke off during trimming. Glue stuff down really well in the previous step, take small Z pases.

I actually started out a little wide, and stepped in by 0.01 each pass. That way I could slowly sneak up on the right diameter.

I didn't make enough full reptiles, so I had to fill in spaces with bits of heads and tails that I just cut off. This was a pain in the neck, but came out okay in the end.

Step 7: Glue on the Border Pieces, Trim the Whole Table Out.

Glue on the borer pieces. This is a pretty straight-forward step. Just glue them on. Clamps sure wouldn't hurt about now.

This is the point that I trimmed off the full outer diameter of the table. This leaves a really ugly edge. About this time, I realized I'd have to fill in with some wood filler. I used Bondo :-) Seemed to work just fine.

My fist bit was too short, and I wasn't paying attention, so my collet nut gouged the border when cutting down to the bottom of the plywood. I switched bits and finished the cut.

Step 8: Bondo Up the Border. Paint Sides and Bottom.

sorry, no image, but I used bondo smooth out the edge and bottom of the table.

After the bondo looked good, I masked the top off using a garbage bag & blue tape. Trim the blue tape with a scalpel, and it'll form a perfect mask.

Then I painted the sides and bottom with black paint.

Step 9: Use Round Over Bit to Trim and Finish Up the Edge.

After the paint job, I went back to the ghetto 4-axis router. Put in a 1/2" round over bit to create a nice rounded edge on the device.

I didn't photo at this point, but here's the finished edge so you get an idea.

Step 10: Finish the Table Top

For this I chose to use Glaze Coat that I got a Lowes. I used nearly a whole quart because so much went down under the pieces. You'll use less if you are careful about filling seams.

That Glaze Coat is pretty nice -- just be careful to follow the directions. The heat gun does wonders for removing bubbles. But, check every 10-15 minutes during the first couple of hours for new bubbles as bubbles seep up from below, and even come out of the wood itself.