The side table was my first really big reverse method project. I glued the tesserae upside down to tissue paper. The paper was not strong enough to hold the weight of all the glass, so I could not place the sheet of tesserae on top of the table. So I reversed the whole thing. I laid out the sheet of mosaics on a board, spread mastic on the table top, placed the sticky table top on top of the mosaic sheet. I needed some weight to actually presse the glass into the mastic, and at that point a sweet 10 year old daughter comes in very handy as a kind of paper press.
After letting the whole thing dry, I peeled off the paper from the tiles and grouted the mosaic. In three colors. But not after spending quite some time cleaning out mastic that had seeped out from between the glass. Of course it would have been much better to pre grout before placing the mosaic on the mastic, but that would make grouting in three colors quite difficult.