So can you not make a custom icon for Items? or am I just doing something wrong?
<append xpath="/items">
<item name="FryingPan">
<property name="CustomIcon" value="diamondaxe"/>
<property name="CreativeMode" value="Player"/>
<property name="HoldType" value="45"/>
<property name="Meshfile" value="#Other/Items?Misc/sackPrefab.prefab"/>
<property name="DropMeshfile" value="#Other/Items?Misc/sack_droppedPrefab.prefab"/>
<property name="Material" value="Miron"/>
<property name="Stacknumber" value="250"/> <!-- STK loot -->
<property name="EconomicValue" value="26"/>
<property name="Group" value="Tools/Traps,Food/Cooking"/>
<property name="ItemTypeIcon" value="campfire"/>
<effect_group tiered="false">
<passive_effect name="CraftingTime" operation="base_set" value="10" tags="boiledWater"/>
</effect_group>
</item>
</append>