As a token of rememberence, the guests could be presented the same. It is pertinent to state that organising a Theme Wedding necessitates elaborate planning, feedback from close friends and a fine assessment of the interests of the guests. There may be considerable differences in tastes across age groups and communities. Try to assess the number of vegetarians and non vegetarians in order to plan a suitable combination for both of them. Factors such as geographical proximity to the guests' place of work or their residence are equally important.
Most brides often forget the 'comfort' factor before zeroing on their final choice.
It is very important that you choose an outfit in which you can move around with considerable ease. If your theme involves participation by the guests give them some kind of hint about the same by mentioning it in the invitation cards. Alternatively, you can decide to give them a pleasant surprise. More ideas, resource listing, cost factors et al.