mine couldn't be simpler
1 x poly box from shop £freeeeeee!
1 x aquarium thermostatically controlled heater £22
1 x thermometer with remote probe £4 e-bay
1 x ice cream tub £freeeeee!
1 x bag of vermiculite from garden centre £5
half fill poly box with warm water
put in aquarium heater and set temp ( I set at 82 degress)
damp vermiculite in ice cream tub
temperature probe in ice cream tub
float tub in water
close poly box
monitor temps and adjust as necessary over a week
Temps stable put eggs in box and shut lid, check eggs weekly, temperature probe in at all times
100% hatch rate for corns at 62 days on my first ever go, all babies big and strong