Yes, it is possible to make your own brown rice cereal for baby! And it only requires one ingredient: brown rice.
Just pulverize a few cups of dry brown rice to a powder in a food processor.
I would not recommend doing this during nap time! It’s loud, and it took me a good 10-15 minutes of grinding. It makes a decent size batch that can be stored in an airtight container at room temperature.
To prepare the cereal, I followed a recipe from The Best Homemade Baby Food on the Planet. Bring 1/2 cup water to a boil in a small saucepan. Whisk in 1/4 cup brown rice powder and stir for 5-10 minutes over very low heat. Cool slightly, then transfer to the blender and blend in up to 1/4 cup breast milk or formula to get your desired consistency.
The blender step may be unnecessary. It made baby led weaning seem more appealing to me, though, since I am not particularly fond of cleaning the blender (quick tip though, fill it with water and a squirt of dish soap and blend on low to get an easy jump start). You could probably just whisk in the breast milk instead of blending.
I divided the goods into this handy storage container with about two tablespoons in each section.
Let the cereal cool to room temperature before feeding to baby. Serving size is about 1-2 tablespoons to start.