First of all Click Here to open a page with the pictures of the kicker you are going to make. Keep it open as you read this to better understand what I am talking about.
Materials: Some 2 by 4's, Screws, a think sheet of ply wood or wood of your choice for the top of the kicker, the part you will ride on.
1. You have noticed the kicker has 3 supports to keep it really strong at sturdy, first thing you want to do is cut a 2 by 4 so it is 1 and 1/2 feet long. This is the end piece of wood, this isn't one of the three supports the three supports attach to this.
2. Cut out your three supports out of a 2 by 4, each one should be 2 and 1/2 feet long. All three should be exactly the same. Then you will need to cut them all again so they have a curve to give the jump the kick. Take one of the three 2 by 4's you cut (One of the supports) and sketch a couple times the curve you want to cut it at. Keep doing it till you are satisfied, then you will need someone with a bit of skill with a saw or weapon of choice to cut the wood. Cut it once then trace it to the other two supports and then you have 3 identical supports.
3. Take the wood you cut first the 1 and 1/2 foot long 2 by 4 and line up one support on one side of it. Take a couple screws and nail it only from the 4 inch side, the side that is going to be visible when you are finished. Screw in only a couple screws to make sure it stays. Take the other support, screw it to the other side then take the last, measure out the middle of the 1 and 1/2 foot long and screw it to the middle.
4. Take your now fully built frame and cut the piece of plywood that your are going to put on it. Make sure you leave a tiny bit too much of it at the end where you are going to ride onto it. (only about an extra cm, 2cm at max) Take your screws and your screw gun and screw the board into place. Now since you left room on the top of the 1 and 1/2 foot 2 by 4 you can screw screws in without any worry of hitting another screw. Once everything is finished and the plywood is in place go to step 5.
5. Now the tiny bit of wood you left at the end where you ride onto the ramp needs to be cut or some how filed down so it gets thinner and thinner. Find a way to do this, with a sander or something and then test your wheels to see if you can ride on the ramp without any chance of catching your wheels on the wood. If the sheet of wood isn't bent enough and you are worried it is going to rip of or something, or even if you think the ramp could be smoother then this is what you do. Take some big and heavy rocks put them onto of the ramp, try to cover it, then soak the ramp with water every couple hours or just leave it in the rain. Do this for a couple days to a week and it should be bent perfectly. Now go and ride!
Good Luck!
