What materials are needed to separate a single switch with light and fan to 2 switches
To have normal wall switches independently control the light and fan, you need two switched-hot wires between the two boxes. You are probably one wire short, in your present configuration, which means pulling a new wire (if in conduit) or a new cable (if NMC) between the two electrical boxes. Note that if you want to control the fan’s speed from the switch box in this setup, one of the two “switches” has to be a motor controller, just as if you want to control the light’s brightness from there the other has to be a dimmer.
As an alternative approach that seems easier for an amateur like myself: There are remote control units designed to be installed inside ceiling fan housings. Many of them do provide independent control of light and fan; some provide dimmer, motor controller, or both. Versions exist with dedicated remotes, smart-hone integration, or both.In this approach the remote (or your phone, or a smart-home signal) becomes the primary control, with the existing switch still only having the ability to remove and restore power for the entire fixture.
Since I’m playing with home automation anyway, I’m going to go with the latter approach for at least two of the remaining three fans. The one I’ve already done (via a smart wall switch designed for this combination) was in the top floor so pulling a new cable was easy, and that’s true of the other upstairs fan. The three located in the ground-floor extension of the house are on switch loops, and I think they’re NMC so pulling additional wire through seems likely to be much more hassle.
The more experienced electricians may disagree with me on the relative difficulty; pulling wires around invisible corners of houses is not something I have a lot of experience with. I can handle straight lines or mostly-exposed like that attic wire, but…