Grumble alert - AGAIN?

Having, inadvertently, replaced the non colour-coded tops on my last purchase of "Poxy Resin" I had to pierce both tubes with a pin for the next mix.  NOT a stable storage set up.
  They were duly flung and, eventually, (this week) replaced.

When Clicky was in operation with her Gems in the Den she had a setup similar to this - ergo I thought this would be similar to hers and, consequently, spot on.  That, of course, was before I opened it.

The mixing appears to occur ats the components descend that tube.

Here begineth ye grumble(s):-
1.  The amount I required was less than the amount required to fill one of the two supplied nozzles.
2. Said Nozzle is now full of mixed resin, set and unfit for future use.
3. After the next use, I'll be out of Nozzle with 1/2 - 3/4 of the stuff left. Hopefully I can remember to replace the wee black Cap the right way round to prevent another lockout.