Hi Ari, I've attached here a finished up solid version of the chessboard, I think it's got all the things combined ok now.

The main steps I did was that I first focused on getting the board and the tiles combined, when I examined their surfaces I saw that they originally came from a big sphere surface that was many many times larger than the current active trimmed area - that will make some various complications with such a discrepancy in size since some things like intersection tolerance will be based on the overall size of the underlying surfaces.

So running ShrinkTrimmedSrf on those pieces solved that problem - after doing that it was then possible to just select the board and all the times all at once and do a boolean union.

Then like I wrote above I also noticed that some of the legs were poking little pointy parts up either right on or just slightly above the top surface, you don't want to have that kind of thing with a sharp point barely touching some other piece. So to solve that I did an offset of the bottom surface of the board halfway up to construct a surface going halfway through the board. I then selected the legs and did boolean difference with that median surface as the cutting object. That took a couple of minutes to calculate and then it sliced off the tops of those leg pieces that were sticking up too much, then I deleted those. Then after that a boolean union with the board worked ok.

- Michael