To make a bacterial culture you will need an incubator – fermenter. There are a number of these which you can buy, such as :
* Davis & Waddell
* Instant Pot – various brands
You can make your own using a Chilly Bin (Eski):
Lamp Fermenter:
You will need a chilly bin.
Bolt a lamp holder (screw thread) onto a plastic lid (marmite jar). Screw the lid onto a block of wood. Drill power cable hole into the side of the lid & near the corner of the chilly bin, just above the bottom.
A 12W CFL bulb may do.
Incubator:
You will need a chilly bin, plus – heating pad, controller, plastic box, power cable, bolts.
Racks are useful – I made mine from aluminium. You could make a wooden frame. The plastic containers need to be above the bottom of the bin, so hot air can circulate.