Replace Some Spaces & Append Text

I need help looking at text in a cell that has [] around it such as [big red trucks] and copy that text to the end of the cell and replace the "space' between the words and add '+' signs so the result looks like [big red trucks] [big+red+trucks].

example:

This is what the cell looks like before

[big red trucks] cost 5000 in store

This is what the cell needs to look like after

[big red trucks] cost 5000 in store[big+reg+trucks]

there may be additional text after the ']', I need the phrase with the + signs copied to the end of the cell