1Pipes1

When you get past the final barrier, go into the little man hole, pull the lever and a box falls down. Destroy it, build the grapneling platform and use it. Use the next one to get on top of the bunker entrance. Shoot the boxes, build what's left over and push it over the edge. Jump off the bunker, build the access panel, use R2D2 and your in!

Hope that's what you need.