First, you can rummage through the trash pile that's left after repairing an item. In order to Upgrade objects, you must have parts. Parts - Common Upgrade Parts, Plumbing, and Electronics I would read Skill Books and upgrade items around the home until level 4 or so, then start working at the Woodworking Table. If you start this way, you can improve skill fairly fast and begin to make a return on your investment. I suppose it must come with some unseen power tools, for the price is quite high.

You can also start with a Woodworking Table, found under Buy Mode > Objects by Room > Study > Hobbies and Skills. Most Sims will start this skill by trying to repair something broken in the household. To get started, you can read a skill book at the library or by ordering one on the computer. Repairing and Upgrading Objects This Situation calls for the Handiness Skill! You can now set your skill level with t_skill_level major_handiness x (fill in 1-10) - we also have a full listing of Skill Cheats and a master list of Cheats in The Sims 4 -> Press Control + Shift + C then type testingcheats on and press enter.