If this card is added from the Deck or Graveyard to your hand, except by drawing it: You can add 1 EARTH Machine-Type monster with 500 ATK and/or DEF from your Deck to your hand, except "Ancient Gear Box". You can only use this effect of "Ancient Gear Box" once per turn.
These cards can be searched via Ancient Gear Box’s effect.
Adds from Deck to hand
I fail to see how this is useful as a lvl reward. Its only good if you have a lot of Gear Knights your trying to get into play. Sure its a good blocker, but so is a creature with 2000 attack like, idk, Wyvern with Gear Castle effect up.
Since ancient gear awakening this card is absolutely fantastic. Wyvern or ultimate pound can add it to your hand to get an extra ancient gear soldier or frame. Ancient gear workshop already worked in the past. Favo combo now is to discard ancient gear box to GY via gear frame to get gear golem to hand and then use gear workshop to get gear box and gear soldier. Voila, 2 gear monsters and a golem. Fusion time!