For a long time I used drink bottles, especially bottles from sport drinks that had a nipple style top. I then moved to lab squirty bottles which I bought from the same place I got the retort stands. Later, when I upgraded the stand to 2020 extrusion I started using the T33 filter holders.
The lab squirty bottle has a tube that runs through the lid and this makes it easy to turn them in to a Mariotte syphon. A Mariotte syphon delivers a constant rate of flow regardless of the liquid level inside the bottle.
For the aluminium frame I generally use T33 filter holders. A benefit of these is they have threaded connections so nozzles can be easily attached. It is slightly harder (only slightly) to create a Mariotte syphon though.
Another benefit of the filter holders is clips and attachments are available. I use the basic wall clips which I attach to my frame with cables ties. Cable ties are tight enough that the bottles are secure when full and when making drops but loose enough to slide around when I want to move the bottle. They also mean the bottles are easy to remove for cleaning.
Cable ties are a simple effective way to hold the bottles.
The bottles and Valves & Bottle Sets are available in the dropController Shop