Magic Items with multiple parts, different abilities when have both parts

[MNBlockHead]

What is the best way to deal with magic items that come in parts where each part has an ability but together they impart additional powers?

Right now, out of ignorance and laziness I create each part as a magic item and then create a separate item for both parts.

E.g.

Left Eye of the Tiger (gives frightful roar)
Right Eye of the Tiger (gives jungle camouflague)
Both Eyes of the Tiger (gives the abilities of the individual eyes, plus at-will polymorph into a tiger).

[Mergon]

What I did was make piece one of a set count as a Container. Then you put each additional piece into the container part.

Then you have a eval script check to see if a part is in its container. If it is, it activates addition powers on the container item.

In my case its a set of armor that grants abilities and bonus based on power gems that have to be installed in the armor.

[MNBlockHead]

Thanks. I'll need to spend some time learning to write eval scripts. A chore in the short term but a better approach than my kludge.