What I have been doing for open feeding of dry pollen sub is. I use a 6 inch piece of 4 inch pvc pipe. On one end I have an end cap and the other end is a down spout. I secure the caps to the pipe to keep it water tight and then paint them. The down spout converts the round hole into a small square, I like to run some sand paper on the inside just to give the girls something to grip. I then hang this in a tree and keep the opening pointed down to keep the wind and water out of it. It has worked fantasticly for me the past few months untill we started getting real pollen here. Now the girls are no where near them but I am sure when it dries up here they will return to them.