The Mastercraft Mediator, Rolis Hlaalu, is located in the Alliance Capitals of Elden Root, Mournhold, and Wayrest. He sells some plans directly for Writ Vouchers earned through crafting Master Writs. You can also purchase the Hlaalu Journeyman Furnisher’s Document for 10 Writ Vouchers or the Hlaalu Master Furnisher’s Document for 25 Writ Vouchers. These contain random furnishing plans of superior or epic quality.
The Achievement Mediator, Faustina Curio, is Rolis’ assistant and is located next to him in all three locations. She sells all of the retired plans that were removed from Rolis’ inventory for 100 Writ Vouchers, but you must have completed the achievement, “Unsurpassed Crafter.” This requires completing 100 Master Writs. She also sells each of the Storage Chests and Coffers for 200 and 100 Writ Vouchers. You must also have completed the achievement, “Permanent Tenant.” This requires you to own an inn. She also sells Morrowind versions of the Furnisher’s Documents for 20 and 35 Writ Vouchers, which do not require a completed achievement.