This roller comes in two flavors one positive for stamping/paint rolling and one negative for embossing or addign texture to material. I made it to texture bases in greenstuff, sculpey and to texture foam for miniature terrain.
The interior is hollow to save on filament took about 2.5 meters on my machine.
Dimensions are 55mm long 25mm diameter, bricks are ~ 8mm wide by 4mm high
For more interesting textures, roll the emosser twice at different angles.
I was inspired by http://www.greenstuffworld.com/en/22-textured-rolling-pins
You may not need the raft if you have good bed adhesion.