So this is an interesting idea someone just showed me: https://ephemeron-labs.com/new-products-1/8sr4jlt168t5rifluoslpgdys8qwd0
Basically tweezers + XYZ stage and some silver epoxy. Would be super easy to DIY.
Definitely not as slick as a real wire bonder but would probably work fine for low volume and large'ish pads
Could pair it with Norland 130 for a more streamlined system (UV light to tack in place, heat to fully cure later). Not sure how conductive NCA130 is compared to traditional silver epoxy though