I just finished a down quilt and you can see pictures here: 14 ounce 3" loft down quilt
I haven't made anything down-filled since the late 1970's when I made a sleeping bag and sweater from Frostline kits, and a vest. I learned a few things that hopefully others may find helpful.
1) Working with down is not necessarily a messy operation. I transferred handfuls of down from the vendor's plastic bags to the quilt with no significant loss. There was no need to vacuum after I finished. Only a very few stray plumes have shown up in the room. My lessons were:
-Work in a room with no draft.
-Move very slowly.
-If a few plumes or a clump of down falls, don't try to catch them until you're done transferring your handful. Then move in slow motion to gather them and pick them up.
-Don't compress either the source-bag or the destination fabric that would create airflow.
2) Make the baffles narrower than the desired loft. I made my baffles almost the same as the desired loft thickness. The design quantity of down provided the desired loft while the quilt was laid flat, but settled when the quilt was held vertically.
3) I think a 12" square karo baffle spacing is marginally acceptable to maintain even loft.
4) I think the baffled "pockets" on the sides of a quilt especially should be smaller. The sides of the quilt will hang vertically and the baffles should be more closely spaced to prevent settling.
I ended up adding more down than I intended by design to reduce the settling, and ended up with a considerably loftier & slightly heavier quilt than I originally wanted.
The plan is to test it out this coming weekend in the high peaks region of the Adirondacks. Weather forecast is for sub-freezing temperatures at night.