Grind up the rice in the mixer without washing the rice first. To get an even flour, try pulsing the mixer, 3 seconds on, 3 seconds off. It's done.
If you're worried about the coarseness of the flour after blending, or if you don't have a blender, you can use a mortar and pestle. You can sift the flour and re-grind what remains to get a fine flour.
Here's a potato salad and corn mayo pizza made from rice flour. You get an irresistible chewy texture when you use the rice flour (Recipe ID: 2142431).
Rice Noodles (Recipe ID: 2153358)
Story Behind this Recipe
When I noticed that you don't have to wash polished rice if you use it to make risotto, I tried to make some rice flour and it was really convenient. If you make a lot and store it, it's not a pain.
The profile photo (under the katakuriko) shows some finely made rice flour. Rough flour makes for a good texture. If you're concerned, you can use wash-less rice or pre-wash and dry the rice completely before you make it into flour.