Interesting question. Eco-friendly could cover a multitude of things. Like the device you are seeing this answer upon. So really it is perhaps a case of deciding what level of "eco-friendliness" is acceptable. Tools have plastic handles - iron / Stylus. Metal parts in tools - (mining). Packaging contains plastic and card. Waxes contain paraffin wax as one ingredient - derived as a by product from oil. Card - made from trees. In reality all manufacturing has an eco-unfriendly aspect. So it's trying to find a balance of eco-sustainability, and yet maintain a product culture that expects so many things which unavoidably have eco-consequences. We are not trying to evade identification of anything. But where to draw the line of acceptable and unacceptable when the consequences of the internet itself are not very eco-friendly? I hope this answer is ok and helps a bit.
Yes. You can pick and mix any selection you wish. Individual waxes can be ordered here: https://encaustic.com/product-category/wax-block-singles/ or o a single sheet containing all colours with the order button at the bottom after you have filled in quantity(ies) per colour(s): https://encaustic.com/shop/easy-wax-block-mixed-ordering/
High quality wax colour blocks. SIZE: approximately: 11mm x 24mm x 42mm weighing 10 to 12 grams [ * 1 5/8″x7/16″x15/16″ weighing just under 1/2 oz.] Formulated to high safety standards using: Beeswax ; Paraffin Wax ; Carnauba Wax ; Micro Crystalline waxes ; Glycerine Palmitate / Stearate ; Pigments – see individual encaustic art wax block colours for unique colour specific information. *contain no resins or gums.