I made it myself from a 5 mm thick aluminum sheet. Removed the complete AIS, not to gain a few grams, but to create working space on the engine, e.g. for adjusting the exhaust valves.
Just drill 2 6 mm holes on the right spots in the sheet and for the shape use the original restrictor plate that comes out of your bike. It is about 30 minutes work and fairly easy to do with only hand tools.
Oh, and don't forget to also cut a gasket in the same shape as the sheet, and also remember to blind off the hole in the air filter housing. A stainless steel (no rust in my airbox), or even plastic (if you can get it) M12 bolt would do just fine to seal it off, and is easy to remove if you ever want to place the AIS back on.