Prologue: The Battle of Endor - Endor Shield Generator
You'll find six minikits on Endor and you'll need to pop back in Free Play mode once you've unlocked the relevant characters to grab them all.
You'll spot this kit on a ledge to the right at the start of the level. To leave the area you need to build the bricks up on the left. Ignore that for now, and build them over on the right side instead.
Jump up onto the ledge and grab the minikit. It'll be where the blue stud is in this screenshot.
Minikit #2 - Free Play Mode
After destroying the second AT-ST, you'll notice what looks like a twinkling beehive on the left side of the area.
Use force powers of a character like Luke to bring it down.
This will net you the next minikit.
After taking care of the third AT-ST and getting R2-D2 free of the tree trunk, you'll see the minikit up on the walkway of the tree on the left.
Reconstruct the bricks in front of the tree and use one character to lift the platform so that the other can reach the walkway and grab the minikit.
Minikit #4 - Free Play Mode
After collecting minikit #3 and rebuilding the bricks to reach the next area above, you'll spot a pool that you can only interact with using Ackbar.
He'll forage for some dyamite that you can use on the tree to the left of the pool. Head through the now open doorway.
In the new area, head to the right and destroy everything. Rebuild the bricks into three instruments and watch the short cutscene with the Ewoks to get the minikit.
Once you've commandeered an AT-ST and reached the bunker that houses the shield generator, you need to destroy three piles of gold boulders. The first if to the right of the bunker.
The second pile is on the roof.
The third is at the front of the screen. If you approach from the right, your lasers should be able to lock onto them without too much trouble.
Minikit #6 - Free Play Mode
There's a downed AT-ST and a group of troopers nearby. Use a character with the ability to command troopers to round them up.
Have them grapple onto the hatch and yank it open.
The minikit will fall out, ripe for the taking.