I can “save” items that are on players.
Minecraft saves player information (health, position, inventory, etc) in a NBT data file that can be browsed and edited with various tools. Items with attached data (wrenched tanks/machines, entity jars, blueprints, etc) have it stored in this data file as well as long as it’s held in the player inventory (it’s also possible to pull it from the region file if I know about where the container is… but MCEdit is a pain for this kind of work). Once the item is located in the player’s inventory, it’s a simple matter of cut and paste to move it somewhere else.
I’ve done this before for “special occasion” bee species and other unobtainable items.
The only caveat I can offer (and this comes from not having time to play with MFFS blueprints) is block IDs will change in the next version as I’m adding a bit and taking a bit out. Not sure if this affects blueprints or not.