For whatever strange reason, I decided to make a sled for a class project, despite the fact I am from California and have never actually seen or used a sled in real life*. Although CNC routing it is nowhere near as beautiful as a handmade wooden sleds, this is something you can build in about a day with minimal woodworking experience.
Because I'd never actually seen a sled in real life, I based my model off of images I found online. Unfortunately, a friend of mine from Alaska who actually knows about sledding warned me that the "horns" on the front of the sled are a bit dangerous, since there's the possibility of flying off and hitting them. So I'd recommend modifying the model to remove the horns if you plan on riding this.
*Actually, that's no longer true as of last month!
Step 1: Tools & Materials
3/4" plywood (2'x4'), although solid wood is probably a nicer option
1/2" plywood (2'x4')
Steel sheet for the bottom of the skids
Step 2: Modeling the Sled
The sled is designed for easy, zero-fastener assembly using slots and tabs. Since I used cheap plywood, the thickness of the wood varied a lot so there was no way to make the tabs a perfect fit. Instead, I wound up using wood glue where the tabs were too loose and a file or sander for where they were too tight.
I decided to make the plywood for the skids 3/4" and the struts and seating 1/2" to cut down. This was a somewhat arbitrary decision based on what seemed structural enough and not too heavy. It's definitely load bearing, but I don't know how it would hold up if it crashed into a tree (to be fair, I don't know how I'd hold up being crashed into a tree either...), so it could definitely be beefier.
The sled was design in Solidworks, and then the DXF for the parts were exported to Adobe Illustrator so I could arrange them to fit on the sheets of plywood.
Step 3: Machining the Pieces
I routed the parts on a ShopBot with a 1/4" end mill. Depending on the type of router you're using, remember to use tabs or something to hold down the smaller pieces so that when they're cut, they don't pop loose and damage the end mill. (This Instructable assumes you have knowledge of how to use a CNC router already).
The SolidWorks file for routing the part is attached. Unfortunately, since I made this a while back, I can't seem to find the Illustrator files, but depending on the size of your plywood you may have the rearrange the pieces anyway.
Step 4: Cleaning Up the Parts
I used pretty cheap plywood, so there were a lot of surface imperfections. I used wood filler to try to clean it up a bit I also tried sanding it down a bit with a belt sander, which helped a little. Remember if you do that to wear gloves and a dust mask.
In addition to these surface imperfections, I had to do a lot of filing to get rid of the tabs that held the pieces of wood down while CNC'ing (different from the tabs used for the slot-and-tab assembly). For the tabs for the assembly, I also had to do a bit of filing. Because using the end mill leaves a radius, the inside corners of the tabs need to be filed down to right angles so that everything slots together at the end.
Step 5: Assembly
I used wood glue to hold everything together, especially where the tabs/slots were a bit loose (you'll need clamps to hold it together while the glue is drying). For places where the tabs are a bit of a tight fit, try using a rubber mallet to bang them in.
Step 6: Finishing
This is where I admit that I cheaped out a little bit and didn't really finish the sled, since I wasn't in a place where I could use it anyway. However, if you do live somewhere with lovely sledding slopes, I'd recommend painting the whole thing with a waterproof varnish, and putting either metal or PVC rails on the bottom of the skids. Then, try not to hit any trees!