I'm building a rudimentary lathe MacGuyver style....
Ok, it's to hold the band over the front of my TLR lenses to interlink the CPLs ;0) I've had a quote from SRB to machine a custom piece then realised that a Cokin A adaptor ring will do the same job but may be too large. Before I progress anything with SRB I wanted to check for an off the shelf option.