Just make one, it's very simple. To get the curve of the case there just place tracing paper over it and then just simply stab the pencil through where the mounting holes are. To make the case saver part of it just cut a slab of 1/2 in. sheet aluminum or billet to the traced curve, and then dremmel out a bunch of hollow spaces in it so it can sort of collapse and increase the impulse time if the chain breaks. You can also bend a chunk of aluminum to the curve by torching it with propane and bending it over a pipe. Be cautious with the torch, aluminum will burn and turn to ash if it gets too hot.