I have reported on the folks over at 4D before.
Recently they have begun an expansion into selling items that are of interest to gunsmiths. First they added Dakota Bolt handles, these are the same bolt handles that Brownells once carried. High quality cast steel, these are the weld on variety of knobs. They tell me grip caps from Dakota will arrive this week and these will be added to the site as soon as they are ready to ship.
Another interesting product they have added is Laminated wood stock blanks. They already have several color combinations in stock, and they can provide a bunch more with only a one week delay. Just visit the new page on their site to see what is available.