DIY Homemade Car lift

I don't about wood construction for a lift. I have seen a car or two fall off wooden ramps and dollies. But I could be wrong. I just bought this lift it was used for $600 it runs off 120v and has a 3ton capacity and raises the car just over 48 inches. just my .02 cents

I have been semi looking for a lift like that. It would be great for me do do body work with my bad back.