I am not sure but no Boonie/Tilly Hat in the base game I suppose, so you need 2D/3D models of that (for deployment / in-game, respectively).

Sorry I didn't know but in a famous mod that hat has been already implemented.
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2840563363

So, for just a personal use, install the mod, make a copy of the hat, then change its stats with Santa hat's one.

That's a cool screen shot. I will try to see what I can do but I have no technical know how what so ever. Thanks for it.

Originally posted by Cosmo:

That's a cool screen shot. I will try to see what I can do but I have no technical know how what so ever. Thanks for it.

HI, just read the comments in the screenshot. Anyway, highly probable that the mod is outdated/incompatible because is more tha a year old.

I think its 2d/3d models isnt outdated, but I am sleepy and in my bed.
I will write how to, but plz wait for a while.

First, read the guide about how to make mod, but the mod you make is very easy, so I will write most of it and you may need lacking part from the guide.
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2277558398

Download IOV mod main file from:
https://www.nexusmods.com/doorkickers2/mods/48?tab=files
Unzip it.
Files you would need are:

\IoV_!base\models\humans\attachments
(contains 2d model (dds). 3d model (khm).
there are some variants of bonnie hats, and you need only one of them,
but unnecessary ones will not do something bad.)

\IoV_!base\localization
(contains texts in game. you only need a few of them, but unnecessary ones will not do something bad)

\IoV_!base\equipment\head_attachments_iov.xml
(contains the hat description)


The base game's file would be there (for my win11 PC).
C:\Program Files (x86)\Steam\steamapps\common\DoorKickers2

Santa hat is in \data\equipment\head_attachments.xml
open the xml with text editor (notepad or something).

Put your mod here.
C:\Program Files (x86)\Steam\steamapps\common\DoorKickers2\mods

You need folders / files like below
\my Fancy Hat mod\mod.xml
make it with text editor, the text would be like below:

<Mod
title="my Fancy Hat mod"
description=""
image=""
author="Cosmo"
tags="Armor"
changeNotes=""
languageMod=""
gameVersion="36"
/>


\my Fancy Hat mod\IoV_!base\models\humans\attachments
\my Fancy Hat mod\\IoV_!base\localization
These files are borrowed from IOV. Copy and paste them.

\my Fancy Hat mod\equipment\my_fancy_hat.xml
make it with text editor, the text would be like below:
Note: BORROW FROM IOV means copy and paste from \IoV_!base\equipment\head_attachments_iov.xml


<Equipment>

<Bind eqp="my Fancy Hat">
<to name="Rangers"/>
<to name="CIA"/>
<to name="Nowheraki"/>
</Bind>
<Helmet name="my Fancy Hat" inventoryBinding="Helmet"
tooltip= BORROW FROM IOV
description= BORROW FROM IOV
img=BORROW FROM IOV
>
<MobilityModifiers moveSpeedModifierPercent="50" turnSpeedModifierPercent="-20"/>
<ConcealmentModifier add="-3" />
<RenderObject3D BORROW FROM IOV>
</RenderObject3D>
<Params protectionInfoText="@equipment_protect1" allowNVG="false">
<ProtectionArc degrees="360" coveragePercent="0" piercingProtectionLevel="0"/>
</Params>
</Helmet>

</Equipment>


Launch the game and enable the mod.
If crushes, you miss some files or making xml.
If your trooper drop the hat etc., the 3d model needs some fix and I don't know how to.

P.S.
Edited a bit for better readability.
Sorry I was sleepy.
What was the memopad?