You could do this yourself pretty easily, but it's time consuming. I've done similar things and it's just a lot of nitpicky fit and check work. You can start with a piece of plastic, posterboard, etc., and spend a lot of time making everything fit. Then transfer that to a piece of sheet metal and start cutting. If you have a buddy at a machine shop, you could digitize the pan at the right height and transfer that directly to a laser or waterjet instead. The only thing that isn't visible in the picture is how the sheet metal piece attaches to the pan, it's hard to tell if they have welded in a bracket or are using some cast-in feature that already exists in the pan.

If you're going to be doing any welding on the pan, make sure you get the upper gasket surface flycut, it will probably have some warping from stress concentrations and heat distortion.

 

Had it not been aluminum I could easily make that for you for a fraction of the Mugen price.

However my welder is not setup for aluminum.

 

yea thats really all i want, is someone who is willing to weld aluminum. I kno i cant!