We are absolutely loving your on-line tool. We're using it to teach introductory circuits to first-year college students.
One major feature I like about TinkerCAD is that it looks realistic, meaning, circuits looks like they are built in the lab.
I'm finding, however, several key non-idealities are missing when it comes to laboratory test equipment:
1. Function generators have no series resistance, when, in fact, every function generator has a 50-Ohm series resistance.
2. Multimeters have no series resistance when measuring current. Typical values are 5-Ohms when measuring current up to 100-mA. Making this a variable would allow it to measure higher currents. Regardless, every current meter adds some resistance in series.
3. Multimeters have no parallel resistance when measuring voltage. Typical values are 10-MOhms.
You might say that adding non-idealities makes things annoying. Nevertheless, students have to "learn to use laboratory instruments," just like they have to learn to create circuits.
Thank you very much!