Maybe something thats emulsified? I was thinking some ewax, stearic, water (preserve of course) and Monoi butter, maybe some vitamin E and jojoba also? This is off the top of my head but maybe 100g water 10 g Monoi butter 10 g jojoba 5 g vitamin e 7 g Ewax 5g stearic (I'd use liquid germall plus) I'm basing that off a clay mask I've made before, it made a nice thick cream, and those are all ingredients known to be in conditioners so I think it might work. worth giving a shot! It wouldnt be too huge of a batch so you wouldnt be wasting a whole lot of ingredients. The water you might need to adjust, I added almost 50 grams of clay to that base recipe, so depending on how thick you would want this hair mask to be, you could adjust the water.