There are plans for a five-frame nuc here on BeeSource. If you want four frame size, take off about 1-1/4" to 1-1/2" from the width. Take the bottom stand and attach it with four 2-1/2" or so length decking screws to the brood box. All mine have attached but easily removable bottoms. I also made a screened inner cover for venting during transportation that I secure with 1" or 1-1/4" screws. The screen isn't used except for very hot days or crowded nucs that I'm moving.I am looking to build a large frame 4 frame nuc. I would like the bottom attached to the box. Does anyone have any measurements or suggestions. Thanks for any help.