moving both arms at once

Looks like you have a few solutions, but wanted to share mine in case it helps anyone.  Right now I have a character that is holding a box with two hands.  It's a pretty cartoony character, so I could get away with making both of his arms and the box one layer.  I added puppet handles at the shoulders, and elbows of each arm, adding tags appropriately.  Then I added just one dragger handle between the two hands on the box and labeled it for BOTH right and left hands.  I then added the Limb IK behaviour and now when I drag the hands/box dragger, the arms bend and move together!  It took some fiddling with adding a few other pins here and there on the box, but it worked pretty well!

It will be very helpful to give a concrete usage example. ..
Your application power is wonderful!　🙂
Thanks for the funny video!

Translated Japanese into English.

I have added "limb IK" in three positions.
1) Top Level
2) Right_Arm layer　（Check "Limit range"）
3) Left_Arm layer
I uploaded a sample puppet to Dropbox.
And it is explained on YouTube.
Check it out, please.
"limbs IK” is working.
Thank you.

https://www.dropbox.com/s/6votogee24xrk5i/ver_4_Japanese_WOMAN.puppet?dl=0

https://youtu.be/rDIPump7h08

I used translation software to convert Japanese to English.

Previously, the video puppets I uploaded had open arms by default.
If you rig with your arms open, you can move symmetrically like a mirror.

Perhaps you are designing a puppet with your arms closed.

So I think rigging will move in the same direction.

When designing a puppet, it's a good idea to keep your arms open.

If you have to design your puppet in a closed position
It's a little difficult, but there is a way.

1) Add dragger behaviors to both your right and left arms.

2) Check "Limit range" in the dragger behavior parameter of the right arm.

3) Move your right arm outward.

4) Move your left arm outward.

5) By moving the right arm outward, the left arm also moves like a mirror.

However, this method is very troublesome.

I hope that the time version will make it easier to move the mirror.

Thank you.

https://youtu.be/wvgHbLUZm24

It works! Thank you so much!

Japanese to English with translation software

(1) 　Standard puppet described by Chloe.
(2)　Usually the left and right sides move separately
(3)　But　Add the "Dragger" behavior to the Right Arm in rig mode.
(4)　Mouse dragging moves left and right arms at the same time

This is just Please give it a try!

The video I uploaded to YouTube is in Japanese but may be helpful.

Thank you!