When it comes to coins I take a piece of sheet steel, fold it over to make a u and then put my quarters/dimes in. Once I get them in and situated, I clamp them in a vice and weld the end of the sheet steel together. I found this works nicer than trying to wire them together. Place them in the forge, get them up to temperature ( if you rake the side with a steel pick and it takes a bit of the semi-liquid copper with it) and then either use the vice to push it all together, or tap everything together with a hammer. Hope this helps.
Adam