Here's my method
Y'know, whenever I've had to build a demo chute, here's what I do:
I rip down some OSB to whatever width is going to be appropriate for the slide. 16" and 24" are handy figures, but it can be whatever is best for what you're intending to send down. Then I take some coil stock aluminum, which we usually have left over from various exterior jobs, and overlay the OSB with that to create a nice slick surface. Then add some 2x4 or 2x6 rails to the OSB/coilstock slide to give it rigidity and provide some sidewalls. Stagger the OSB joints with the 2x material of course, and add some scab blocks where you have butt joints if the chute will be over 16' long. No need to have it buckle under a load of plaster.
Once the slide is done, we secure it to a window opening, hole we've knocked in the wall, or whatever is most convenient, and build some legs for the bottom of it. Set the height at the bottom to allow for a wheelbarrow, trailer, dumpster, or whatever you're planning to fill up. Add an extra set of legs in the middle for support if it's a long chute.
Rough description, I know. Here's a pic to illustrate a simple variant.