Reduction examples from the strongly NPC problem 3-PARTITION
Prof. Erik Demaine has contributed the wonderful (video) lecture of "Algorithmic Lower Bounds: Fun with Hardness Proofs (Fall'14)". In particular, lectures 2 and 3 are devoted to the reductions (directly or indirectly) from $\textsf{3-Partition}$.

For example, Lecture 2 is concerned with several variants of Jigsaw puzzles. The results are collected in the paper "Jigsaw Puzzles, Edge Matching, and Polyomino
Packing: Connections and Complexity". Its abstract says


  We show that jigsaw puzzles, edge-matching puzzles, and polyomino packing puzzles
  are all NP-complete. Furthermore, we show direct equivalences between these three types of
  puzzles: any puzzle of one type can be converted into an equivalent puzzle of any other type.




Most probably you have known these results and this video lecture. However the wonderful lecture may be also useful for other people.