Morphing constructs

[Jervis]

Enhance it as a +1 morphing/sizing weapon, and a cursed morphing effect, as well (curse: opposite effect; turn into non-weapon objects of the appropriate size category). That way it can turn into both any weapon of any size category and any non-weapon of any size category. Use that in conjunction with the above.

At least using shifting instead of Morphing + Cursed Morphing, that’s just too cheesy. Plus shifting is cheaper anyway. Just need to be OK having a baby fire elemental inside your car.

As for the question, make a Effigy Creature (complete arcane) and find a way to give it shapeshifting abilities. Probably a custom item or just casting a spell on it. Alternatively, dominate a mimic somehow. You could also, theoretically, make a stronghold using stronghold builders guide rules for multiple forms of movement. Just make the smallest stronghold possible.