I like to keep my CA in the fridge. I let it out because it was nearing empty and I had dripped some and it now had an anti tip cardboard bottom. I forgot to put the top on tite and knocked it over. I managed to get everything off the bench and nothing important was coated but it did a nice job of refinishing my workbench top.
I no longer keep the big bottle anywhere near my bench. Nothing worse than having your favorite beverage become part of your workbench.

My turn..

On my current build (a 12 frets slope D in sassafras/bearclaw sitka), I wanted to make a shell purfling for the 1st time of my life on the soundboard edge.

So I cut the binding channels by hand, try to make a clean job.
I install the wooden purflings, the teflon strips and the ebony bindings.

Then I remove the teflon strips and begin to fill the gap with the little 1" shell pieces I had bought at australian MOP.
Right from the start, I found weird that the strips were standing really higher than the purflings, and there was a lot of room between the shell and the wall of the gap left by the teflon strips.
Another weird thing: the shell didn't look to be as shiny as I supposed it would be..
I was thinking to myself "well.. I will have to fill all this room with ebony dust and superglue, it will be messy.. and the shiny part of the shell will eventually appear after levelling by sanding"..
But anyway, I continue gluing those high, floating, not shining shell pieces one by one, with medium viscosity CA, adding some ebony dust on the way.

I work my way from the soundboard center seam to the waist of the treble side of the body, and suddenly I have a flash in my head.
I look at the remaining shell pieces properly and find that there are 2 shiny sides and 2 greyish horrible sides..

You've got it.. I had started to glue the shell pieces on the wrong side!... I was gluing them in an upright position, the shiny sides were facing the walls of the purflings..

At no moment I realized that I was doing it wrong, I was in the process...

So I had to remove all my binding and purfling, destroy the shell with a chisel and start all this treble side again... then ordered some shell inlay, because I hadn't enough pieces to finish my job.. 10 days to wait..

I found myself to be a real dummy on this one..
Worst mistake in 4 guitar builds..

q.

......reminds me of the pick guard i tried to polish out and then realized it had plastic cover on it ...

My turn - When working on an OM earlier in the year I decided to use a power sander to level the sides. I paid such close attention to the binding on the side facing me, but forgot that sanding was happening on the back side as well....you guessed it.....sand through! Ugh! It pretty much went away when the preamp hole was routed out, but it was devastating at the time and for the entire rest of the build. And I can not blame cough medicine, either...it was ALL ME! Only hand sanding sides for me from now on.

I think Quentin takes the gold, though. Puzzling over the pieces being too narrow and tall and not looking shiny, without taking the time to closely examine them until there weren't enough left to redo it... that's grade A doofusry there Hope it turned out good the second time.

I bent the wrong way, flattened with a clothes iron and then re-bent the same ukulele side incorrectly two times In a row. The third time was the charm although the side was a little rough with some small cracks in the waist. Repaired with CA and usable.

I bent the wrong way, flattened with a clothes iron and then re-bent the same ukulele side incorrectly two times In a row. The third time was the charm although the side was a little rough with some small cracks in the waist. Repaired with CA and usable.