Whether u have lava or cactus u can make an incinerator from them
Step 1: The Lava Incinerator
U need to make a square and make a back to it. Make a hole in the middle and put lava in it
Step 2: The Cactus Can
Make a 3x3 hole and put a sand block in the middle of it. Fill in the corners with whatever.make another layer with dirt but leave the middle uncovered. Then add a back to it.