Hint 5

Start by placing an H‑piece. Insert it so that its sharp apex sits at the exact center of the bottom face, leaving a cavity in the middle.

Putting another H right beside it will block you almost immediately, so add a T‑piece next. If you try to match faces of identical shape, there is only one way the T will fit.

Continue to match identical faces. From this point on, each remaining piece has a unique position and orientation.