It turned out to be a blissful day.

Anders and Auggie came over and Anders decided he wanted to make a crossbow.  I explained I don't have any proper material, etc. etc.  To no avail.  So we googled image crossbow.  Printed out a drawing by Leonardo daVinci of a plan for a huge (like a WMD) crossbow (with a little man sitting on the top)

I cut out a crossbow shape from a cardboard box.  Of course, it was flimsy and frustrating.  Then I remembered I had some little pieces of scrap wood in the shed.  I found the perfect two pieces.  By this time Auggie was ready to go home with Eliza, and Anders stayed on.  We worked on it for a long time--and I taught him how to hold a hammer, how to saw using the vise (I have one in the shed) and why it's better to hammer something on a solid surface rather than the table we were using.  I put garden gloves on him, and set him to sanding rough edges.  He did everything by himself.  Part way through the project, it occurred to me that this project was worthy of a cub scout badge (I told this to den leader, Gunther.)

At home Anders added a rolled up paper arrow, and attached rubber bands so that the thing actually did work--sort of!  It was an exquisite day spending time with a child who is so focused on making things.