This is holder features a non-slip bottom and a rod going through to hold the spool and keep it from falling out and rolling away if dropped.Print the model. Cut 1 1/4" piece of 2.8mm filament to use as the rod to hold the spool into the holder and secure with a dot of hot glue on both sides. I found a piece of spongy rubber at the local craft store in the felt section and glued to the bottom with Elmer's type glue so it wouldn't slip as I pulled the solder out. Works Great ! Enjoy !