Doing a small area on side of door. When guy put door in he chipped all the plaster and it was in hunks. I wanted to put fresh plaster in there, but when trying to do this with a trowel, it just kept falling off onto the floor. This area is only about an inch wide. I wondered if they made some kind of bag , kind of like a frosting bag they use for decorating cakes etc. to put the plaster in and then squeeze it into the wire mesh?

Look in the drywall dept at HD, they have some there.