This model consists of two parts:

1. The stone border: Use a black or dark color. I recommend default settings (0.4 nozzle, 0.2 layer, no supports)
2. The portal: For best authentic look, use a purple color. I recommend a plain print sheet with a smaller layer hight (0.4 nozzle, 0.1 layer, no supports)

Assembling:

1. After printing it, place the two portals back to back so their shape matches on both sides.
2. Together slide them into the big block of the portal.
3. Place the top row of stones on the portal with the grove towards the portal sheets.
4. If it fits, add some glue and permanently combine the parts