After your first home is ready (small one room house that you got to pick the color roof for), head to Resident Services to trigger a dialog scene. Afterwards, speak to Timmy who asks for your help gathering supplies so the shop can be built. He will need donations of 30 hardwood, 30 wood, 30 softwood and 30 iron nuggets. You can gather the hardwood, wood and softwood by using an axe on the trees around the island. For the iron nuggets, you will need to use your axe on rocks. Once you gather the materials, talk to Timmy and inquire about building a shop to donate the materials. *NOTE: He only accepts donations in amounts of 30 (i.e. 30 hardwood, not 29 hardwood). When you have gathered all of the materials, you’ll need to wait a day in real time for it to be ready.