We have a giant tub of bricks that my kids used to tip out, stare at, and abandon. Too many choices, no starting point.
The build cards fixed exactly that. A single picture on a card gives them somewhere to begin, and once they have copied it they almost always keep going on their own.
I keep the cards on a metal ring in the brick tub, so the invitation is right there when the lid comes off.
Tip
Six cards is plenty. More choices means less building. If your child finds copying frustrating, sit down and build your own version alongside theirs instead of correcting — they copy the modelling, not the instruction.