Terrazzo is one of my favorite mediums. It's a little hard finding sources for the materials but once you do it's very rewarding. Terrazzo can be bright using epoxy colors or more muted using cement. The pictures shown here are all using epoxy. Below the supply pictures I have added a work (actually 2 works) in progress that I am working on now. I hope this is helpful.
I usually take a drawings or design and rework/play with it on my computer so I can play with colors and different heights and widths. I used to print out the final design at whatever size I wanted (3' X 5' or whatever) then trace it onto the substrate. Now I just print it out on a 4"x 6" photo paper and enlarge it onto the board to whatever size I need. Small pieces can be easily drawn freehand. These two designs were taken from stain glass patterns (the examples above are from modified quilt patterns). Both of the substrates shown here are very light-weight as they have a foam core and the final pieces will be easier to hang on a wall. My previous pieces were on heavier backer board. The third picture is the design drawn out with marker onto the substrate. Picture 4 & 5 - I have started gluing down the zinc strips.
The last picture here shows how I pick out aggregate for each color placing the aggregate onto paint chips.
The last picture here shows how I pick out aggregate for each color placing the aggregate onto paint chips.