^ way i did it was saw the stock trigger down, almost in half, to get rid of the curved piece. then from there constructed pieces of carbon fiber to build a body around. i put holes in the carbon fiber trigger face to adjust the screws, and also added magnets.
if you dont wanna mess with carbon fiber, id try out extra hardened bondo.
outside of the evil blade trigger, or finding a used tbo somewhere, this is your only option. goodluck.
im not telling you this is the best way to DIY, and im surely not telling you to do it, so dont come back blaming me if you cut your finger off or something. but goodluck.