Are there any? 
Every single Tunnel I've seen/used is always 3x1 tiles on the grid at the portals, but Personally, a 1x1 one would be good for putting two next to each other and have them be aligned, or just having one that doesn't take up a lot of space.
I guess the same could go for a 2x1 as well...

Every single Tunnel I've seen/used is always 3x1 tiles on the grid at the portals, but Personally, a 1x1 one would be good for putting two next to each other and have them be aligned, or just having one that doesn't take up a lot of space.
I guess the same could go for a 2x1 as well...