I just made my sled yesterday after months of thinking about it. I've seen some seriously sweet set ups, one of the best was a home made job I found on a firefighting training forum, (dont ask how I got there, I was drunk and havent a clue how to find it again)
Considered buying a ready made sled, considered the old tyre and bit of wood options, thought about the old wheelbarrow filled with cement, thought about a big piece of chain, ( I live in a mining town and you can get hold of old chain with links the size of basketballs if you know where to look).
But after months oftripping over a piece of conveyor belt rubber that was left over from the flooring of the home gym, I finally had an epiphany! I decided to try and use that. After cutting to size and cutting a hole and threading with 1 1/2 inch rope, not that easy I might add. this conveyor belt is nearly an inch thick and all I had was a stanley knife... And then I had my sled! Hooray!!
Got warmed up and started off by just pulling the rope arm over arm, fairly hard, thought I could do better and put a 20kg plate on and it felt like the weight had tripled. tried towing the damn thing with the rope around my waist , much much harder than I thought it would be.
The friction of the rubber just on grass was ridiculous and after 20 minutes of
alternating towing and pulling I was shattered
End result: One very effective sled, nearly indestructable and total cost was 20 bucks, 15 dollars for the stanley knife, the rubber was free and the rope I got for $5 from a garage sale the local scouts were having and had to get rid of it
Just got to work up the courage to use it a second time