Hanayama Puzzle: Keyhole Lvl 4

Here is a challenging maze. At first glance, the two pieces have simple concave and convex angles on their flat surfaces. However, when the two pieces intertwine, they take the shape of a 3D maze. You must twist and turn them around. If you rush without thinking, you will come to a dead end. Be careful as you may end up going around in circles.The theme is "groove." Designed by Vesa Timonen from Finland. Hanayama is known worldwide for challenging puzzles and quality manufacturing. Can you take the pieces apart, then put them back together again? Hanayama cast metal brain teasers have 6 levels of difficulty, and each puzzle is Mensa-rated. Level 4 puzzles are considered challenging by most puzzlers.