Galil accessories are more widely-available than the platform’s popularity might suggest, but one of the accessories that’s always been a bit of a unicorn to me is the Galil Ultra kit. It was made for Galil SARs (the ones with a 13″ barrel), and used what appears to be IWI-branded CAA products to produce a product-improved Galil with more modern features (collapsible stock, accessory rails, ergonomic pistol grip). You could build one yourself by tracking down the appropriate components, but it would be missing the IWI branding (which, IMHO, is what takes it from “home-build” to “authentic”).
From a historical perspective, the Galil Ultra is more important than it might seem, as it’s one of the forebears of the current Galil ACE. The ACE is essentially a mash-up of the Galil MAR (left-hand charging handle system), the Galil Ultra (furniture), and the Magal (polymer lower piece). It is certainly interesting to see how IWI combined the best parts of these guns to create the ACE, much like they did with the Tavor and X95 to create the Tavor 7.
However, I did manage to track down the “manual” for installing the kit. It’s a simple sheet with fairly obvious instructions, but does show how relatively mature the product was. I’ve uploaded it here as a PDF for your viewing pleasure.