Was playing around tonight at work, crunching some numbers and looking at fertilizer ingredients. Pretty sure I'm not going to travel this path, but for future reference, I'll post this here:
If one were so inclined to make their own "Bloom Booster", the fine folks at Greenleaf Nutrients tell us that their Bud Explosion is made up of Monopotassium Phosphate, Potassium Sulfate, and Magnesium Sulfate. In order to get the same blend ( 20 P, 41 K, 1 Mg, 10 S), you would mix in the following amounts.
1 Part Magnesium Sulfate
6 Parts Potassium Sulfate
4 Parts Monopotassium Phosphate
Combine all 11 parts total into a container you can seal tight and mix the powders. Per Greenleaf's directions, feed 1 gram per gallon of water (on top of your base nutes) during bloom.
All ingredients can be sourced from Amazon. The Magnesium Sulfate (Epsom Salts) would probably be cheaper to buy local. Just don't get the stuff with scents, oils, or other crap in it.
Keeping with tradition, we'll call this bloom booster Faux-Explosion®