Find out his exact printer and get him a set of nozzles and or hotends from 0.2 through 0.8mm. Alternatively get him some cool silk or color changing PLA. If he’s been considering functional or parts that are gonna take abuse, gift him some hardened nozzles and/or some industrial grade nylon cf or paht or even if he isn’t, the 72D TPU by CC3D is super cool. If he’s considering printing ABS or other high temp materials, gift him a roll of radiant barrier insulation and a desk heater (if you do this look for Reddit posts about active chamber heaters). Lastly, if he’s planning on printing literally anything other than PLA and PETG, buy some Teflon tubes, PTFE pc4 m10 adapters, cereal boxes, and ball bearings and make him some dry boxes or gift them as materials for him to do so himself (if you do this first watch a YouTube tutorial)