Make coffee coasters from your old Christmas tree
Step 1: Trim
Begin by trimming the branches off your Christmas tree. I have a reciprocating saw which made quick work of it. A hand saw would work as well.
Step 2: The Log
After the branches are removed cut your log into manageable pieces a couple feet long or so. Now you will want to start slicing 1 inch thick (or whatever you like) disks off the end of your log. I secured the log in a vice and used my reciprocating saw again. For the most part I could cut fairly evenly freehand. A large mitre or radial arm saw would be easier and more accurate but just use what you got.
Step 3: The Disks
You should have a ton disks of varying size and shapes. Select the ones you want and sand them down to make them flat and level. You wouldn't want your coffee to spill out cause your coaster isn't level! I used a pretty heavy grit sandpaper, but make it as smooth as you like. If you have power tools you can do this pretty quickly. I put a sanding disk on my angle grinder and set the coaster on top of sandpaper I secured to my work bench. The sandpaper held the coaster pretty well while sanded the top of the coaster. Again, use what you got and be safe.
Step 4: Draw
Sketch lightly with pencil a drawing of what you would like on your coaster. The smoother your wood the easier it is to erase the pencil if you make a mistake. Don't worry if you can't erase all the pencil. A quick light sanding after burning your design will take care of it. I'm fortunate to have an artist in my family who sketched these designs but I'm sure you could get some tracing paper to work. I have even laid a photo on a disk and burned through the photo paper to make a design.
Step 5: Burn
I have a small electric wood burner that we got from Walmart for $10 that came with 5 different tips. I used a fine tip and thick tip on this project. Start by tracing over the pencil with the fine tip then use a thicker tip for shading in the larger areas. If you never used a wood burner just experiment first on a couple of your extra disks. If you make a mistake you can't fix, just flip it over and try again or you can sand it down. I like to do all this on a large oven safe dinner plate so I have a place to set down my wood burner which sometimes gets almost to hot to hold. Be safe and be careful, you can give yourself a nasty burn or start a fire.
Step 6: Finished
Sand lightly if you need to touch them up. I like the natural look, but you could seal these with a clear sealant of some sort or even use a light colored stain.