Crossword puzzle maker--https://www.armoredpenguin.com/crossword/

This is another website I've used frequently in the past, but am just getting around to posting about now.  Actually I've referenced this website in my "Activities that can be used for any Grammar Point" workshop.  
At the time I said:

Crossword Puzzle (Materials: Crossword puzzle worksheet.  Possibly an answer sheet ) (Preparation:  Make the crossword--usually about 20 minutes)
Make a crossword puzzle containing the target grammar point. 
There are various online resources for this, but I like: http://www.armoredpenguin.com/crossword/ since it allows you to save the crossword as a PDF file, so you can save it in your folder and keep it for future use.
Variation: Crossword Puzzle Treasure Hunt
Remove the questions from the bottom of the crossword, and give the students only the blank grid.  The questions are written on a separate piece of paper, and then are cut up and put all around the room.  (They can be deviously hidden, or they can be placed in obvious places.)  Students are put into groups, and given one crossword grid per group.  They must go around the room to find all the questions, and complete their crossword.  The first team to successfully complete their crossword grid is the winner.

But I wanted to make a separate post here, because I also want to index this in my list of materials for any vocabulary set.  (And indeed, practicing vocabulary is the more natural application of a crossword puzzle anyway).