The simplest approaches that use common parts all use two op amps configured as needed and switching the output between them. To that end, you can:

1. Use op-amps with a shutdown pin. Those are usually designed for such shenanigans.
2. Control op-amp supply with an external transistor.
3. Select the output using an analog multiplexer. The output resistance will be 50-200 ohms depending on what multiplexer mode you use.
4. Select the output using a homebrew switch.

External output switches can be configured in two ways:

1. Outside the feedback loop: op-amp’s feedback is taken from the op-amp output pin, and the switch comes after that.
2. Inside the feedback loop: the op-amp feedbacks are taken from the output after the switch, and the switches are between the op-amp output pin and the feedback network inputs.

The switch-inside-feedback-loop approach will work even with bipolar transistors acting as switches. Using complementary transistors the switches will be bidirectional and pass current going either direction, preserving the output characteristics of the op-amp, with the feedback compensating the C-E voltage and emitter impedance.

The simplest approaches that use common parts all use two op amps configured as needed and switching the output between them. To that end, you can:

1. Use op-amps with a shutdown pin. Those are usually designed for such shenanigans.
2. Control op-amp supply with an external transistor.
3. Select the output using an analog multiplexer. The output resistance will be 50-200 ohms depending on what multiplexer mode you use.
4. Select the output using a homebrew switch.

External output switches can be configured in two ways:

1. Outside the feedback loop: op-amp’s feedback is taken from the op-amp output pin, and the switch comes after that.
2. Inside the feedback loop: the op-amp feedbacks are taken from the output after the switch, and the switches are between the op-amp output pin and the feedback network inputs.

The switch-inside-feedback-loop approach will work even with bipolar transistors acting as switches. Using complementary transistors the switches will be bidirectional and pass current going either direction, preserving the output characteristics of the op-amp, with the feedback compensating the C-E voltage and emitter impedance.

Below is an example implementation of this concept.

For optimal performance, the switching cells are current controlled, not voltage controlled. This improves linearity and headroom, so that the output voltages can swing fairly close to the supply rails - this is limited mainly by OA1 and OA2, not by the switches.

^{simulate this circuit – Schematic created using CircuitLab}

OA1 is the x2 amplifier, OA2 is the x(-2) amplifier. Q1-Q4 are the switches that connect the op-amp outputs to the output node. The feedback is taken directly from the output node. D2 and D3 limit the output swing of the op-amps according to their role. OA1 is limited to 0.5V to +6V relative to the input voltage. OA2 is limited to +0.5V to -11V relative to ground.

R100 is the output load. It is at the edge of what TL071s can drive. When the output load is lighter, the current reference resistor R20 can be increased accordingly.

Q10-Q13 are the current steering control driver, and amplify the 0-5V logic drive signal to +/-12V.

Q20-Q22 form the positive current source, Q23-Q25 form the negative current source. These currents are used to switch Q1-Q4.

Q26-Q29 are differential current steering pairs that route the positive and negative current to either upper (Q1-Q2) or lower (Q3-Q4) switch cell.

R25-R27 form the voltage reference for the current steering differential pairs. R21-R24 adapt the control voltage for current steering use.

And here is its performance:

The switch control currents: