First prototype was based on OPA810 amplifier and +-12V supply voltage. The tweezer tips were permanently attached by soldering:

It was very promising, though the bandwidth was limited to about 50 MHz. However, it was clear that tweezer tips are mostly useful for probing between IC pins, and other uses would need different accessories.

Initial plan was to try to push the cost as low as possible, to around $50 USD sale price. However this would limit the performance a lot. Instead it seems better to have more versatility by having accessories for different voltage ranges and purposes - one amplifier can be extended with cheap attachments.

Switchable accessories will require readjustment of the compensation & CMRR trimmers, but that should be a quite fast process using e.g. the calibration output available on most oscilloscopes.