New wood looks a lot different than old wood. Old, unfinished wood often has a dark, dull gray color resulting from oxidation over time. When stained and/or finished, new wood will continue to look noticeably different than old. In order to cleanly integrate new parts into an old case, the new wood needs to be aged.......
Aging of wood cannot be achieved with stains or finishes. What is needed is a means to actually oxidize the wood fibers, but in a much short time than occurs naturally.
There are products on the market for aging wood and they all work to one degree or another. As an alternative to commercial products, I have found that some common household products can be used to very effectively oxidize and age wood.
The needed solutions are simple to make an use. The results are very impressive..............
Combine this treatment with some careful physical distressing and you can convert a cheap craft box from Michael's or the Hobby Lobby into an ancient coffer suitable for all kinds of eldritch artifacts.