stock:
https://www.shapeways.com/product/8GRU2K5NS/silentshot-rdp-stock-adapter?optionId=61066675&li=marketplace
https://www.shapeways.com/product/RCHZUD79U/rdp-stock-assembly?optionId=61317781&li=marketplace
thread adapter:
https://www.shapeways.com/product/7NETG77AN/rdp-spectre-threaded-adapter?optionId=93467544