Is Lockdown a packing puzzle? Well, I guess it probably is. It's also my first puzzle comprising of pieces in the shape of linked spheres.
LockDown is a Stewart Coffin design (#271-A). Also made by Stewart Coffin for Rob Jones' Exchange Puzzle at IPP35 in Ottawa, Canada this last August. I am not sure the species of the woods used but the puzzle is well made and feels solid and sturdy. It measures about 10cm wide and 7.5cm tall in the assembled state. The spheres are around 2.3cm in diameter.
The puzzle consists of 3 different pieces, each formed by linked spheres. The puzzle came un-assembled and the object is to pack all 3 pieces into the triangular tray to form a pyramid. One edge of the tray has a curved recess to facilitate access of the pieces.
To form the pyramid outside of the tray is not too difficult. With some thinking, you can probably figure out how the final shape would look, given that there are just 10 spheres. Its the packing that requires a lot more effort. The instructions are also explicit that no force is required.
While I figured out the shape of the pyramid pretty soon, it took me the better part of an hour before I managed to get the pieces into the tray. Some experimentation is required to get the right orientation of the pieces and aside from this, the movements also require twisting and rotation. Indeed once the pieces are inside the tray, you could grab the top few balls and lift the entire puzzle off the surface it's on. Truly "locked down".
There are not too many moves involved to solve this puzzle; no need actually since the shapes of the mutil-sphere pieces are enough create a good deal of confusion. Although there are only 3 pieces, the packing is more than moderately challenging and pretty tricky.
To put it another way, the Lockdown is just the right level of difficulty for an Exchange Puzzle. None commercially available but Rob may have some extra copies for sale, just maybe.