Redo fuel tank appearance

As suggested by ghosteh

This also adds an optional material parameter to the model panel's UpdateModel() since you otherwise can't draw the material on the tank

lua/acf/entities/fuel_tanks/box.lua

@@ -42,7 +42,8 @@ FuelTanks.Register("FTS_B", {
 	Name		= "Fuel Box",
 	Description	= "Scalable fuel box; required for engines to work.",
 	IsScalable	= true,
-	Model		= "models/fueltank/fueltank_4x4x4.mdl",
+	Model		= "models/holograms/hq_rcube.mdl",
+	Material	= "models/props_canal/metalcrate001d",
 	Shape		= "Box",
 	NameType	= "Tank",
 	IsExplosive	= true,

lua/acf/menu/items_cl/engines.lua

@@ -202,7 +202,10 @@ local function CreateMenu(Menu)
 
 		ACF.SetClientData("FuelTank", Data.ID)
 
-		FuelPreview:UpdateModel(Data.Model or ClassData.Model)
+		local Model = Data.Model or ClassData.Model
+		local Material = Data.Material or ClassData.Material
+
+		FuelPreview:UpdateModel(Model, Material)
 		FuelPreview:UpdateSettings(Data.Preview or ClassData.Preview)
 
 		FuelType:UpdateFuelText()

lua/entities/acf_fueltank/init.lua

@@ -188,6 +188,7 @@ do -- Spawn and Update functions
 		local FuelType = FuelTypes.Get(Data.FuelType)
 		local Limit    = Class.LimitConVar.Name
 		local Model    = Class.Model or FuelTank and FuelTank.Model
+		local Material = Class.Material or FuelTank and FuelTank.Model
 
 		if not Player:CheckLimit(Limit) then return end
 
@@ -201,6 +202,9 @@ do -- Spawn and Update functions
 
 		Tank:SetPlayer(Player)
 		Tank:SetScaledModel(Model)
+		if Material then
+			Tank:SetMaterial(Material)
+		end
 		Tank:SetAngles(Angle)
 		Tank:SetPos(Pos)
 		Tank:Spawn()

lua/vgui/acf_panel.lua

@@ -320,7 +320,7 @@ function PANEL:AddModelPreview(Model, Rotate)
 		self.NotDrawn = not Bool
 	end
 
-	function Panel:UpdateModel(Path)
+	function Panel:UpdateModel(Path, Material)
 		if not isstring(Path) then
 			return self:DrawEntity(false)
 		end
@@ -364,6 +364,12 @@ function PANEL:AddModelPreview(Model, Rotate)
 		self:DrawEntity(true)
 		self:SetModel(Path)
 		self:SetCamPos(Center + Vector(-self.CamDistance, 0, 0))
+
+		if Material then
+			local Entity = self:GetEntity()
+
+			Entity:SetMaterial(Material)
+		end
 	end
 
 	function Panel:UpdateSettings(Data)