@Catherine_Bernier the hot glue application we did we fix mounted the glue gun and took the part to the glue gun.  We used a Power Adhesives TEC 7100 gun which is pneumatically operated so we could drive it off a solenoid valve.  It does require human intervention when its time to load a new slug but we used sensors on the slug feeder and on the slug chute to know when to ask the operator for assistance.  We were placing pretty small beads of glue and so it did not require intervention very often.