I created a model with 2 different materials (one with transparency and one with sandstone), is it possible to print them in one model like this below? Thanks in advance!
No, but what you could do is print the FCS part, and encase it in transparent resin. Like these http://www.traderscity.com/board/products-1/offers-to-sell-a nd-export-1/real-bugs-in-acrylic-resin-lucite-and-novelty-gi fts-248635/
This would be the best option. Take the FCS part and make a small box for it to sit in, then use a clear epoxy or polyurethane to encase it. Otherwise there's two other ways of producing a "different" colour inside a clear part using 3DP. - SLA: Using a clear material you can "overcure" sections by scanning it with the laser multiple times (or using higher laser powers/different infill param's). I've seen parts with 10 different shades of yellow incased in a clear shell. - Objet: Using VeroClear as the outer material, and any of the other Objet materials for the bug inside. Only a Connex printer is technically capable of this. Shapeways doesn't offer either of these processes, but hey, the more you know
If you don't mind the interior model being white, you can exploit the wax support material in FUD like I did with my Kraken in Crystal - the squid is a wax filled hollow space within the block of FUD