Chapter 4: The Eravana - Freighter Battle
There are four minikits in the first area and you'll need to revisit the section in Free Play Mode to pick them all up.
Minikit #1 - Free Play Mode
After bypassing the toxic area with Finn, switch to a droid with the translation ability to open the door to the left.
Head over to the left, destroy the objects to get a pile of bricks, and reassemble them into a First Order terminal.
After using the terminal, prepare yourself for a brief confrontation with a Rathtar.
Once it's buggered off, nip into the hole in the wall to pick up the minikit.
Minikit #2 - Free Play Mode
Staying in the same area, reassemble the bricks from the destroyed terminal into a BB-8 panel and use the droid to charge it.
The minikit parts will be blown out of the fan to the right. Rebuild them for number two.
Minikit #3 - Free Play Mode
There's one more minikit in this secret area. Use the force to open the panel to the right of where the Rathtar broke through.
Destroy the parts inside and reassemble them into a platform.
Use it to jump onto the open panel and reach the minikit.
Minikit #4 - Free Play Mode
Continue through the level until you reach the sealed door with an access hatch next to it.
You'll need to send BB-8 through to the other side.
Use the force to pick up the oversized key on the right and get the pieces to build a minikit.