Re: 5 frame nuc entrance?
I make my nucs to the same design as my hives so all the bottoms are separate and the entrance is the same as a hive with a bottom board. A few of the bottoms have been screwed to the first hive body for the reasons others have stated, makes them a lot safer to transport in the back of the SUV. All parts are interchangeable and I can add additional 5 frame boxes without messing up the bee space between them. This is clearly not the least expensive way to go but it works for me and the 20 some nucs I use.
Thankfully, the bees are smarter than I am. They are doing well, in spite of my efforts to help them.