First she should request them after the attic planning scene (research the final upgrade in the top line first, then give the girls free evening when Gwynn requests it and keep visiting the upper lobby in the evening during that day until you trigger it), then, after she asks for materials you need to gift her one sublimation gem (green, the one you use for bombs and diamond rings, can be brought to you by Nyx, earned during the portal conquest or bought in the shop), one unit of golden nails (can be made by upgrading stacks of 10 nails or, very rarely, gotten from the cellar barrel), and unique scroll from the portal dungeon game (after Gwynn tells you about it descend to the second level and open the chest, then you get the prompt for opening the secret trapdoor, bring twenty spectral bombs and save beforehand).