<ol start="5">
<li> Grinding flour:</li>
</ol>
<ul>
<li>It is permitted to grind kernals into flour for the sake of [using the flour during] the Moed. This applies even if one could have ground the flour before the Moed, and intentionally delayed it until the Moed.</li>
</ul>

Shulchan Aruch HaRav | 5. Grinding flour on Chol Hamoed

Grinding flour: It is permitted to grind kernals into flour for the sake of the Moed. This applies even if one could have ground the flour before the Moed, and intentionally delayed it until the Moed.