I use cardboard in my wood shop to protect my work surfaces; to collect plastic or wood shavings from the lathe; to produce a test runs on my laser engraver. These hacks saves me both time and money. Most of my cardboard is source via dinner purchases from my favorite pizza store, however, at Christmas the UPS/FEDEX deliveries become a main staple! I use the lid of the pizza box only if there is no grease on it, which is most of the time. At my house this source of recyclable material is plentiful, and free if you count the total cost of the purchase the pizza!
In addition re-purposing pizza box tops, I also recycle paper towel cardboard tubes and plastic grocery bags. I store the plastic bags from my purchases (actually my wife does 95% of the shopping) inside the paper towel tubes until I (or my wife) return to the grocery store. Putting the bags in the tubes conveniently keeps them together until they are taken to the recycling bin.
USE 1 - GLUING PENS:
I ALWAYS put down a section of cardboard onto my workbench when using CA (cyanoacrylate adhesives) glue or epoxy. Most of the time I use CA glue is when I'm going to make a pen. The process of making includes gluing a brass sleeve into the pen blank, CA glue holds this tube in place. CA glue is a quick drying glue (sometimes referred to as super glue). A small amount of glue often runs down the face of the pen blank and if I were to put that directly down on on my workbench those two will become one when the glue dries! To prevent this I place a piece of cardboard under my gluing efforts. If the pen blank has a bit of glue on it and it adheres to the cardboard I just rip the pen blank off the cardboard and small section of cardboard will be attached to it. If the pen blank were to have become glued to my work surface I will either destroy the my workbench or the pen blank when attempting to separate them. The first picture above shows a pen blank that would have been attached to my workbench had I not used the cardboard - note the glue on both the cardboard as well as the pen blank.
CAUTION: CA glue should be used in a well ventilated area. Also take care not to get it on your hands as you can easily become attached to something...or you might get "webbed fingers" lol I do keep a bottle of the CA glue debonder on hand for any glue accidents.
https://www.instructables.com/id/Woodturning-a-Plyw... is another Instructable that I have created that provides instructions on making a pen out of plywood.
USE 2 - COLLECTION OF WASTE FROM THE LATHE
Most of the time I turn wood on my lathe, however, sometimes I will turn acrylics or plastic. I keep a pizza box top under my lathe to catch either the wood or plastic shavings. When the pizza box top is nearly full of wood shavings I dump them in to a 5 gal bucket I keep near my lathe, and when that is full I dump that into my compost heap. I also use the lid to collect plastic shavings from my lathe as well, however, those go into the trash. I leave the cardboard under my lathe all the time to make clean up easier.
The second picture above shows the pizza box under my lathe collecting wood shavings. The third picture shows a golf ball being drilled and the plastic waste being generated, while the fourth shows the plastic pieces that have been captured by the pizza box from the drilling.
USE 3 - PROTECTING THE BED OF MY LATHE:
When I turn acrylic pens, or use CA glue to apply a layer of finish onto my pens. I wet sand during the final coats them to give them a top quality finish. The problem is that water and iron (the bed of my lathe) don't "play" nicely, if water gets on the bed produces rust! Wet sanding is done with the lathe on and the spinning pen will spray water or possibly drip water onto the bed of my lathe if I don't protect it. I use a small piece of cardboard placed on the bed of my lathe to protect it from water from my wet sanding. The spray from the spinning pen is caught on the cardboard preventing it from landing on the bed and rusting it. I use these pieces of cardboard used over and over, if when the cardboard wet I just make sure it doesn't become soaked through. If any water seeps thru the cardboard or drips on an unprotected section, I wipe it off quickly. I also spray my lathe bed with WD-40 to prevent rust from forming from the humidity.
An added benefit of an application of WD-40 is that it lubricates the bed making the banjo and tailstock easier to move.