Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:5020649.

I've always rather liked Inferno Pistols in 40K but couldn't find a cosplay version. This reuses the grip, trigger, and pins from the excellent 40K Rogue Trader Plasma Pistol by Diehard2501

https://www.thingiverse.com/thing:3863387

The other parts were built in Tinkercad and aren't any specific version of the weapon but are rather inspired by several different designs - the rounded power cells (or whatever they are) are more common on older models, the front end is more modern.