It depends on what you want to achieve- do you want them to be good at simply following directions & producing a 'product' that looks only like what you want? Or would you rather encourage creativity, imagination, inventiveness, design skills & independent problem solving?
There is so much time for limited adult-directed work when he is older, a young child's creativity should be protected at all costs, because it is very hard to regain it once the notion that "cats shouldn't look like that" or "this is the correct way to draw a face" has set in- this attitude stifles creativity.
For the 3-4 year olds I work with, I prefer to provide a range of resources & techniques, perhaps demonstrate different ways of using them, then provide appropriate scaffolding during the project with open ended questions or prompts so they don't get frustrated when something doesn't work. e.g When making a door for a cardboard play house- we went to go look at hinges on a real door, then talked about what similar materials we had & the most secure methods we knew of attaching them.
In my experience this 'support' approach facilitates a wider range of deeper level learning, rather than just 'the child can follow steps 1-5' & produce something exactly as it says on the box. I would rather encourage entrepreneurs & inventors!