I’ve found some sites involving virtual instruments. They can be really helpful, especially if there are instruments within reach. You can find them in the links below:
The first site is a virtual guitar. It shows different chords and allows you to play notes of different keys and types. The only downside is that you can only play notes within the triad (ex. c-e-g-c) of whichever key you are in due to only plucking the open strings.
The second site is a virtual piano. It allows you to press any note on the keyboard and play all of the chords. It is only in the key of C, but if you download the full version you can play chords in all 12 keys and it’s free.