How can I pull out some stones from a bag randomly?

Hello to everyone,  i'd like to know if on Roll20 i can put some stones in a bag and pull out them randomly.  Ex: i choose to put 4 white, 3 black and 1 red stones. I have to extract randomly two of them. I need the system to show exactly wich of the stones came out.  How can i accomplish this?   It's the system of an Italian RPG called OMEN.  I hope i explained myself, english it's not my motherlanguage...  Thanks! 

The best way to do this is with a card deck. You can weight the deck (so, put in an image representing each colour stone, and set the weight of white to 4, black to 3, red to 1). Then each time you shuffle the deck it'll be reset to that number. You can deal the cards, which represents drawing the stones, and recall them to put them back in the bag.

I was thinking rollable table but the card deck would work better.

Thanks for the advice. But how can i create a card deck? 

You will need a 4 images. The back image of the of the cards, an image of the white stone, black stone, and red stone. Try to get them all the same size then you will need to upload them to your account. The link below will explain the feature more. Card deck . Youtube tutorial video I found. It is old but still covers the basics.

GiGs said: The best way to do this is with a card deck. You can weight the deck (so, put in an image representing each colour stone, and set the weight of white to 4, black to 3, red to 1). Then each time you shuffle the deck it'll be reset to that number. You can deal the cards, which represents drawing the stones, and recall them to put them back in the bag. Can you assign a weight to cards? I think this is reserved for rollable tables. In case I am right, just create 4 white cards, 3 black cards and 1 red card.

Yes, but the numbers of the stones change anytime... It can be 1B, 2W, 3R, or 5B, 3W, 2R etc... It changes every time you have to take a test... 

I created the deck with the 3 images, but this weight option i can't find that... I will search more tomorrow, now i have to go.  Thank you all for the advices. 

I do not think there is a weight option for cards. You can weight a rollable table, but it will never run out of stones. Use this method: Create a deck of one stone each. Make it an infinite deck (never runs out). Set "In others hands" to only show backs. (so they identify the stones) Deal yourself (the GM) a random assortment of cards, based on whatever criteria you use to set up the test. Ask the player drawing stones to hover over your hand a Steal a Card . They can make multiple requests at the same time, or do it sequentially. As GM, approve the requests. They will now have blindly chosen from a finite, random subset of stones.

Roberto M. said: I created the deck with the 3 images, but this weight option i can't find that... I will search more tomorrow, now i have to go.  Thank you all for the advices.  Keith is correct (naturally), I misremembered, you can't add a weight. But you can add multiple copies of the same card. So you can add the white stone 4 times, the black one 3 times, and the red one once, and you'll get what you need. Just shuffle and draw, then recall when you want to restore it.