I can't take credit for finding the tiles, one of my friends was at Home Depot and saw modular shed flooring tiles so we went and checked them out. They are 2 x 2 and interlock with tongue and groove. And they are only 6 dollars each. So it's only 36 bucks for a 4 x 6 table. It's not crazy cheap but compared to the GW table it's a real bargain.
The first set we tried to use gravel and flocking but that sucked. The seams showed and the gravel was constantly falling off, I never had a chance to paint it as I had to keep putting more gravel on it. Sucked big time!
Here's an old pic of it .. back when my Blood Angels were pretty new..
1.) Buy the tiles from Home Depot or Lowes .. I'm sure plenty of places carry them but they were in the flooring section of the Home Depot we went to. They are made of wafer board and have a plastic base glued to the bottom.
2.) Then I prime them with Kilz Total One. It's a latex stainblocker primer that I brush on. You can use whatever you want but Kilz is awesome and covers greats so one thick coat and your are on to the next step.
3.) Next brush on the undercoat. For the concrete board I used a grey which I had picked up from AC Moore. They were on sale for 3 for a dollar so bonus! I brushed it on rough so it would have a rough real look.
5.) Clear coat the boards when the coverage looks good and is dry. Here is the finished brown table (below), when I put the table together this time I flipped the one board the wrong way so you can see an edge in the middle but normally there isn't a seam (well a color seem, there will still be a slight one no matter what but that's the nature of joining multi pieces together haha).
There are numerous products out there and they all seem to work equally well. I haven't had any issues with any of them.
I made a part two with more information in it, check it out.