This is a repost of an old tutorial I did on LucasForums. The original discussion thread is HERE.
So, one benefit of plot usable items is that if they have an activate property you can use them even if you don't have them equipped, so long as the item is in your inventory. But one thing I've noticed is there are over 200 existing icons, and the engine only supports up to 255 (well, 256 if it accepts 000, but I've never actually checked). So there isn't much room for your items to have custom icons like there is with other item types. However, there are a whole bunch of icons left over from K1 which are not used at all. So I made a list of all the ones I could find that are currently used (it's not inconceivable that I missed some):
22
7
10
12
16
17
23
25
29
35
42
55
56
59
60
61
62
63
64
65
66
67
68
71
72
77
78
84
85
86
88
89
90
91
92
94
95
96
98
99
100
101
102
103
106
107
108
109
110
111
122-251Again, those are the ones that are used. If you use one of those, it will affect other items in the game. So don't use them. 69, 70, 74, 75, 113-122 and 252-255 don't exist at all; the others exist but shouldn't appear in the game. And in case you don't know... Plot Usable Item is a base item type that appears in your inventory but cannot be equipped. It is similar to the Aesthetic Item type, which uses the same icon set (and thus meaning there are even fewer numbers for us to use). The difference between the two types (I think) is that if a Plot Usable Item has an Activate Item property, the item will appear in your action menu. This allows you to have access to usable item equipping it - meaning a) you don't use up and equipment slot, so you can equip other things, and the whole party will have access to the item. I don't think this feature was actually used in the game, however. To create a plot usable item, create a new item and set the base item type to Plot Usable Items. Model Variation determines the icon number. The icons themselves are located in ERFs -> Texture Packs -> ***_GUI -> I, and the files all begin with "ip_pltuseitm_" (e.g. the unused holocron is ip_pltuseitm_072.tpc). Some additional information: 1 is a book of some kind. 11 is a Mandalorian helmet. 12 (used), 28, and 35 (used) all have Czerka logos. 15 has the Star Forge symbol on it - I think it's the Sith medallion from K1. 24 and 39 are crystals. 32 is the krayt dragon pearl. 33 is a Sand Person. 40 is Sith armor. 44-53 are all keycards. 72 is a holocron (107 is also a holocron, but is used for an HK part). 79 is the dancer's outfit, but the icon that is actually used is ia_slave_001 (I believe this is true of the Sith and Sand People disguises as well - so they wouldn't even be used in K1). 83 is another dancer's outfit, resembling Leia's more than the one in the game. Anyway, long story short, feel free to use any number that is not on this list. The only issue would be compatibility with other mods that do the same thing.