Here's a way to make a 3"x5" Rolodex compatible folder to hold related cards together. The cards can be removed, relocated, and replaced together.
The folder is made from a single 8"x5" index card. In this example, I used a blank blue one.
Hold a 5"x8" index card in portrait orientation and a 3"x5" Rolodex card in landscape orientation.
Fold the large card BACKWARDS from the bottom of the smaller card.
The back will be longer than the front.
Using the hole punch set up for making Rolodex-compatible cards from 3x5 index cards, punch the folder as though it were a regular card, on the side that has the folded edge.
Use a scissors to cut from the folded edge to the punched holes.
Trim the back of the card to the same height as the front, with a bulge for an index tab.
This is what it looks like when held open:
Write a label on the index tab. Individual related cards go inside the folder. They can be removed, relocated, and reinserted together as a unit.