Need Help with Warp Zones

Hi all.
I'm trying to get warp zones to work, and so far I've been successful(ish), but I've run into a few problems.
Firstly, I'm trying to make some funky circular "walk-in warpers", but my skills with custom shapes ((de)intersecting etc) aren't that great.
Is there such thing as a circular sheet brush? Coz I wanna make a circular zone portal to cover my warp zones, and then intersect and export the brush in order to re-use it.
I've attached a .rar file with the beginnings of my warp zone testing map.
Any help no matter how small would be appreciated.
Cheers for reading.
Shin.
I'm trying to get warp zones to work, and so far I've been successful(ish), but I've run into a few problems.
Firstly, I'm trying to make some funky circular "walk-in warpers", but my skills with custom shapes ((de)intersecting etc) aren't that great.
Is there such thing as a circular sheet brush? Coz I wanna make a circular zone portal to cover my warp zones, and then intersect and export the brush in order to re-use it.
I've attached a .rar file with the beginnings of my warp zone testing map.
Any help no matter how small would be appreciated.
Cheers for reading.
Shin.