You can create a raised, 3D, Cob sculpture (also called Bas-Relief) right on top of your conventional drywall!
First: Choose the image you’d like to sculpt onto your wall.
Second: Draw the image on the wall. Creating a grid can help you to make sure you are drawing it to scale.
Third: Mix a traditional cob mix (2:1 clay:sand) and add chopped straw. You will want to screen your clay as to get any rocks and chunks out.
Fourth: Begin to apply small ‘golfball’ size clumps of cob to the wall; it helps to throw it onto the wall from about 6″ away. Once you have a small section covered in ‘balls,’ begin to smooth them all together using a flattened palm. You can go as thick as 1″. Anything thicker and you’ll want to first apply roofing nails to the wall to act as ‘claws’ to hold the cob.
Continue: Until you have the desired shape. Let this dry out until ‘leather hard’ before adding anymore or doing any decorative work.
Next: Begin to add extra layers to embellish the sculpture and add mosaics. Don’t forget to always re-wet your dried out cob before adding new!
As your cob sculpture dries, begin to compress it using a flexible trowel or a plastic lid (yogurt lids work great!). Stay on top of cracks as they appear by buffing them out as they come.
Paint around the cob sculpture to enhance even more.