I've heard tell that a few people who are fans of Morrowind (so.. obviously really ancient, right?) have been looking for a "mirelurk merchant" to be hidden in one of the worlds of the Fallout franchise for some time. Don't know why you'd want that, like, at all, but here it is, a Mirelurk Merchant.

So, yeah. He's a merchant, and he sells Mirelurk.
"Mirelurk merchant". Right?

If you really want to find him, he's been sighted puttering about in Sheng's lagoon for a while before he goes back to his beloved house(boat?) in the islandy area of roughly the bottom right hand corner of the map, but up a little. I would check the Diamond City Waterfront first. Maybe a map with some nice red circles will show up on somebody's homepage or fansite.

I can't have this just be another rudimentary NPC mod, for obvious reasons, so there's some Mirelurk he merchants in weapon form, too. You buy this thing up and a separate Mirelurk or potentially various Mirelurk(s) will give some promotional materials away for free (they're not really merchants, you see), polluting the ground.

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This mod implements "Lurkenminer systems" by turning mirelurks into minelayers ("minerlurks") which follow the path established by an L-system.
If you represent a real life military or defense contractor, please don't steal this idea, because that would be "bad", in several senses of the word.
[Mostly in the sense of it being a completely impractical, theoretically unmotivated, and difficult to implement weapons design of dubious value.]

There are ten commonly-encountered l-systems available: Koch curve, 2 types of fern, a Sierpinski gasket, a snowflake, the Gosper & Peano space filling curves, a Penrose tiling, and a couple other ones. In a perfect world, I'd link this up with my Papyrus Computer Club programmable computer and interpreter mod so that you could enter your own L-systems, and maybe perform robot operations with a Mirelurk from user programs. Sadly, we don't live in a perfect world.

When (or shortly before) you first encounter the Mirelurk Merchant and acquire the weapon, the L-systems will be evaluated in-game in parallel and the resulting LOGO-like/"turtle graphics" program will be cached for later use (some notifications will show you the progress of this computation, and you can also see the number of steps of computed L-systems in the L-system selection menu).

Once some or all of the L-systems you want to use are loaded, you can go to the menu by meleeing with the Minerlurk Seed selected (this may be easier if you are unarmed, and just attack instead of using the grenade button). Here you can choose an L-system from the list hinted at above, and you can also choose to cycle through several options. "Hostility" refers to whether you or a third party will "own" the placed mines. You will get blown up easier if this is on. "Sloppiness" refers to whether the placed mines are frozen in place (so that you can see the pretty plane curve) or havok'd (so you do not have to deal with too many floating mines). Clumping refers to the degree of separation of the mines (Medium, High/Small-separation, Low/Large-separation). (Conventionally, excessive hostility, sloppiness, and/or clumping are thought of as undesirable qualities.)

You can change the mine to be emplaced. By default, the mines will be Miremines, which are eggs that bust open and spawn Microlurks, which are too small to hurt anybody significant directly, but which can run around and cause mischief and spread low-level radiation (and also interesting lighting at night). Turrets are an option, although maybe not a good one. You can also choose an item from your inventory to be put down as a "mine". If it is one of the main mines or grenades in the game, it should work like it normally should, except that the precise version used will not blow up due to damage. Why? Well, when you use a minerlurk or minerlurks to create a big and decorative minefield, it is rather a little disappointing if the whole thing goes up in one blinding bang and then is completely gone. These automated minefields are a bit more "fun" to kite raiders through, because they save a bit of themselves for later. Regular items will just be duplicated all over the ground -- use them as liberally as you personally would use a comical texture brush in Photoshop.

If you are happy with your selections, throw the Minerlurk seed and it should create a Minerlurk that will lay out your L-system. If you want it to stumble around less and be faster, crouch while you watch.
As with anything that makes a bunch of things in your world, this is probably a better fit for messing around with than using in your playthrough.