version 1

Surprisingly not that difficult. Fortunately I already own all the tools needed.

First get two spoons. I combined a Vargo unpolished spoon (19g/0.67oz, 8.5 inches) with a Lixada polished bowl spoon (17g/0.6oz, 9 inches). I like the bowl shape on the Lixada. The handles of both are the same shape (this is important).

Obtain a thumb screw, small nut, and washer. I went with size M5. I purchased galvanized hardware because it was less expensive and I wanted to see if my idea worked. Now that I'm comfortable with my design I have ordered stainless steel hardware. I ordered a shorter thumbscrew (shorter thread and flatter head) as the one I used is too long.

Measure twice, cut once. The spoon with the desired bowl will be the longer piece. I also allowed for a little over an inch of overlap.

I used a Dremel tool with cutting disk to cut the spoons. One cutting disk per spoon. I buy cutting disks in bags of 100 so have plenty.
I used a drill with titanium bits. I found going straight to the larger bit didn't work too well so drilled a pilot hole with a very small bit, probably a 1/8. I then used a bit that was about equal in diameter to the M5 thumbscrew. The bits are loose in a bag so I don't know the exact measurement. I eyeballed it and was close enough.

I used files of various shapes to smooth the rough edges.

Assemble.

Open it's about 9.5 inches, closed it's right at 6 inches. The photos don't quite line up but those are the measurements. It weighs 33.5g/1.18oz. It feels quite sturdy, that is, I don't anticipate problems with it bending under a spoonful of rice or couscous or whatever. Might not be strong enough to scoop hard ice cream though. The bowl is angled from the handle slightly so making the folding handle longer not really practical, unless of course the bowl angle is adjusted.
spoon before.jpgspoon after open 1.jpgspoon after open 2.jpgspoon after closed.jpg


version 2 will use smaller stainless steel hardware so should weight a few grams less. I may try securing the nut to the spoon with JBWeld also.