Hi Mazdak, Chimera cannot currently merge two maps into a single map. It can only save a single map and allows writing just a zone or a subregion or a hand-erased modifications, and allows a new origin, grid spacing, and file format. We would like to add the ability to merge maps. Could you explain your case? Do the two maps overlap each other? How would they be combined if they overlap (added)? Are the grids of the two maps aligned so that all grid points of both data sets are part of the same bigger grid? Or would the data need to be interpolated at new grid points to make a merged map? I have written a script that stacks two copies of a map on top of each other and writes a single new map for making filaments twice as long where the original map contains a single periodic repeat. Tom