Buy a ramp kit to make DIY lawnmower ramps. Ramp kits allow you to fashion a pair of wooden ramps at a fraction of the cost of traditional metal models. Popular brand names include Lund, Highland, RampArts and Keeper. Look for them in hardware stores or online retail outlets. Ramp kits can be bought with metal tops only, or both tops and bottoms. These are components attached to heavy boards allowing the boards to be safely used as ramps. The important components of a ramp kit are the tops, because these allow you to safely hang the boards off your tailgate. Without tops attached, the boards may shift when weight is applied to them. So, if given the choice between buying a kit with tops only or tops and bottoms, you can save a little and go with the tops-only kit.
You will also need a couple of identical heavy boards for DIY ramps. Buy two 2- by 12- inch boards, each the same length. The longer the boards, the less incline on the ramp. Ten feet will provide a nice, low incline, reaching from the ground up to typical tailgate height. If you will be loading the lawnmower onto lower places, say a garden shed resting on cinder blocks, or a trailer with a low floor, you can buy shorter boards as your incline will be lower.
A drill and wrench will be needed to assemble the ramp kit. Follow the guidelines in the instructions for assembly. Usually, this will involve marking where to drill holes for the bolts, drilling the holes and bolting the tops onto the boards. Some kits might include non-stick material that can be tacked onto the boards, helping provide traction when they are wet. Once assembled, you will have a sturdy pair of DIY lawnmower ramps built for a fraction of the cost of traditional sets.