I have created this toggle using brass stampings from two different companies. I have had a hole drilled in the middle of the bar. You simply put a head pin through the hole and make a wrapped loop on the back. You then attach the chain to the wrapped loop with a jump ring.
The bar measures 8mm by 26mm. The ring measures 17mm round not counting the ring at the top. The hole measures 8mm. The toggle pictured has a nice verdigris finish that I have applied myself, as I do all my verdigris pieces. You may opt for a nice brass ox finish if you wish.