Josh Plan ahead, work slowly, and use sharp tools..I lay out my mods on the molds I am working on with black sharpie. Then scribe where I want to take out the metal. Then start to take out the metal untill I feel like I am close and cast a few to see how close I am. Go back and finish the metal removal and polish the mold. I have a vertical mill and and flex shaft tool to help me remove the metal. Sounds like you should be able to do a barb with a dremel tool.I have seen that done with a very small drill but I have found that a dental drill works best for me check with your dentist for one that he is going to throw away. Dental drills that are not sharp enough for teeth are still plenty sharp to work aluminium. I also use a lub on the dental drill beewax will work or oil of wintergreen. Like I said work slowly you can always take off more metal but it is a pain where pills can't reach to add it back on. Polish out what have removed so it will come out smooth and take any burrs off the face of the mold so it will fit together flush. now your about done just run a fine piece of sandpaper over the face of the mold 400 grit or finer will be fine and you should be home free. I run a fine pice of sandpaper over my molds every 100 or so any way and it helps for some reason. Think the hooks sometimes will mare the surface and cause burrs. Hope this helps.

Redman