I have started thinking about 5) เครื่องสีข้าว especially hand/man-operated device/gadget that can fit by size&by price into households.

I have one idea that maybe some university students can do in group projects: a home/hand cassava flour production/process giving 2 output: tapioca flour and "cyanide" which can be used as 'insecticide' (spray).

Cyanide in cassava is produced by cassava to protect itself. [Soaking in water for 5+ hours; boiling and blanching; fermenting; and sun-drying can remove 99% of cyanide spray -- compare this to other chemicals]. Hundreds millions baht can be saved from importing other (more harmful) farm chemicals. [Over-use of cyanide or any chemical is still a problem.]