The puzzle box looks like there's no way in; no obvious lid; no obvious base. Just a sealed box with no obvious opening.
Alan Boardman designed a mini (actually microscopic better describes it...) box puzzle called the Aha Box in 2004. He presented it in the Edward Hordern Puzzle Exchange at IPP24 held in Tokyo.
This puzzle has been upsized from that so there is enough space inside if you want to include a surprise. It's great to give just as puzzle box though.Puzzle are made from veneered ply wood and blonde wood from Finland Size - 137mm x 85mm x 26mm (space inside the box is 119mm x 64mm x 14mm)