Must meet requirements

• At least one analog input channel,  ±12V-ish
• At least one digital input for triggering, configurable via software
• At least one digital output, configurable via software
• Low power usage
• Wide input supply range (3.3V-12V?)
• Reliable time source for data acquisition (low jitter, high accuracy)
• Web-based user interface for configuration of settings such as:
  • ADC Gain
  • ADC Sample rate (continuous, triggered on input, etc.)
  • Digital I/O (logging/output/triggering)

Stretch Goals

• At least one analog output channel
• Onboard storage for datalogging
• Serial port with web interface (RS232 TTL)
• "Bus sniffer" for SPI/I2C
• Battery power option

Potential issues

• How do we make it as small/cheap as possible?
  • Pre-soldered ESP modules must be weighed against raw chips as an option
  • Power the multi-tool from the device under test
  • Small pitch connector for test probes
• Is input protection critically essential?
  • If the device is cheap enough, can we skimp on input protection?
  • What are the safety ramifications?
  • The multi-tool is not designed with high voltage measurements in mind

Typical usage case

• I need to measure and record the input and output voltage of a circuit I've built, but a typical datalogging setup isn't suitable.  Maybe I'm in the back of the shop, rather than at my bench.  Maybe I'm not near my datalogging computer?  I can connect an ESP8266 multi-tool, and do my datalogging wherever it suits me best.
• I need to measure and record a few choice signals on a piece of equipment that a customer is having intermittent issues with.  I can install an ESP8266 multi-tool, configure it to record, and come back tomorrow to download and analyze my data.
• I need to record a voltage, while simulating an input signal, and I want them to be synchronized.  An ESP8266 multi-tool allows me to do just that, with its analog input recording and digital output pins.