I once had an ACS CX riser made of DymaLux...making a search for it I came to a company named Cousineau who also have a product called Spectraply...there is a note on the website that supplying it may take up to three months which implies to me that the Rutland fire has affected their ability to keep up...you will note a picture on the website of its use in a laminated gunstock...anything that will make a gunstock ought to work for making risers as well and there are lots of laminate gunstocks these days
DDave