units selling items

i want a unit to sell items, so i chose a goblin merchant and replayced the art. ground: none, shadow: none, collision size 10 or something.

But: It still takes as much ground to place as it did before, so i can´t place several units close next to each other. How can i do this?

Plz help :bgrun:

Change the Pathing Map to one of the towers, and lower the collision size to the size of a unit of about the correct size.