I would definitely recommend & encourage smaller type projects or items. Thinner type mini albums, small journals, a personalized pillowcase, a shirt sprayed with your perfume & lots of letters (which you could include pics). Not only do their packs weigh a ton, but upon return, whatever they cannot carry, will need to be mailed back stateside in their military cargo trunks/footlockers.
I made individual 12x12 albums for each deployment. Once my husband returned, I included all the notes, referred to our journals, included his deployment & homecoming pics, etc.
Hope That Helps!