Dunno if this would need to be a homebrew, but picture this: a Goblin with a Heavy weapon mount, but whenever it fires...
As the title says, I dunno if there's a skill I missed (because hooh boy does Lancer have a lot of options to comb through in the grand scheme of things) that would let you change your mech's weapon-mount type or if it'd need to be a homebrew OK'd by your personal GM and other players, but the mental image cracked me up too much to not share.
Take a Goblin, get rid of its one Flex slot, and swap that out for a single Heavy slot. This is balanced out by the fact it's still a Goblin now trying to fire a Heavy mech gun, so you have to do a second dice roll after every shot that decides how many spaces you go flying in the opposite direction from whichever direction you fired toward. Not meant to be meta or make the Goblin a reliable murder-machine, just add some comic relief in the form of a little guy trying their best.