This may seem out-of-the-box, but IMHO if the player vault size was increased (multiple vaults, larger vault, infinitely large vaults, whatever) it would allow builders to stockpile, on their builder characters, all of the comps, ores, refined ores, etc.. that they need to build what they have printed. As it stands, a builder would require multiple "vault-alts" to hold all of the required stock to be able to build everything they have printed. Now since it is a real pain-in-the-rear to do this, the prevailing business model is the one where the buildee goes out, acquires the comps needed for the build, hands them to the builder at F7, the builder presses the button and the buildee gets their gear. Allowing builders to easily vault what they need to go into business, would allow them to provide finished products to the buyer, which would demand that the buyer be charged.
PS Increasing the vault size might make inventory management even more difficult, would it be possible to implement a slash command to switch between multiple standard-size vaults on one character?