We haven't implemented the bundle feature yet.
However, instead of bundles, you might try another promotion strategy for the same products.
You just need to create discount codes for specific products or collections. Check out the video here to learn how to create this kind of promotion: https://monosnap.com/file/aCT00xIvL4xMzK7Zl8PCYz7isxgrq8
Buy 1 piece - price $10.00 (no discount)
Buy 2 pieces - get 20% OFF with a discount code MASK20
Buy 3 pieces or more - get 30% OFF with a discount code MASK30
If you want to have a promotion "Buy 2 - Get 1 Free", please follow this example how to create a discount code in Shopify: http://take.ms/VOzVD
Once complete, you only need to add information about available discounts in the product description (http://take.ms/ftpPS and http://take.ms/TQNh7 ) or promoting your products.
Does that sound like a good alternative?