Source for 58mm-M42 step down ring

I have an infinity objective I'd like to use with a lens. I have the adapter to get from the objective thread size to M42 and now need something that will get me from M42 up to a 58mm filter size. There was a link on photomacrography.net to an eBay seller, but that appeared to be a dead end. Any other sources?

There is a UK manufacturer that will produce custom adapters as well as their regular ones..... http://www.srb-griturn.com/

Contact them at nquiries@srb-griturn.com for a quote.

Bob

Thanks Bob. That's a great resource, will file that one away for future reference. Turns out that somewhere along the way I managed to procure an M42 to 52 and now all I need is a 58-52 step down which should be easy to find.