After realising the organic insecticides were only a single active ingredient (Potassium laurate) and overpriced I launched a chemistry mission.

Based upon commercial retail product labeling, the target solution strength is 2% in water and this has been certified organic by some authority or other. Based upon my recent research, you can't buy it at full strength as far as I know, but you can buy two precursor chemicals: potassium hydroxide and lauric acid. It's an acid-base reaction. Therefore you need to work on equal molarity not equal weights.

1. Obtain potassium hydroxide and lauric acid

2. Weigh out 20.03g of Lauric acid, dissolve in 200mL water.

3. Weigh out 5.61g of Potassium hydroxide, dissolve in 200mL of water. This will get hot so you will need to wait until it cools down.

4. Mix the two solutions. It will give you 400mL solution containing 23.84g potassium laurate (60g/L).

5. Since a 2% solution is 20g/L, you dilute the solution in the ratio 1 part solution to 2 parts water (ie. add 800mL water). So in total you should have 1.2L of 2% product.