Invalid feeding cups (a.k.a. "sick feeders") came in all shapes and sizes and were intended mostly for adults. They however also are found in smaller sizes though rarer indicating children in mind.
From a collector's standpoint one of the most coveted shapes, in my opinion, are the ones with the applied cover extending over the majority of the top and with a rounded opening near the back (see photo at left). I personally also like these because the larger top cover allows more room for transfer designs.
Feeding cups were also made in silver and pewter (see photo below).
Feeding cups came in varying degrees of detail regarding where the spout were placed (see photo at left where one example has a single hole and the other many), size of the spout (from extra large to extremely small - see two example photos below) and placement of the handle (left, right, behind and not at all).
Examples of elaborately shaped 18th Century cream colored feeding cups:
Examples of 18th Century Lowestoft feeding cups:
Examples of 18th Century Isleworth feeding cups:
The "Kirby" Feeding Cup -
I highlight the "Kirby" because of its distinctive two piece design. While never reading its instructions I was always amazed at all the measurements on them, whether or not one was supposed to carry the small vessel inside the larger vessel when transporting it and whether each vessel had its own unique purpose (i.e., medicine vs food, etc.). I also always liked it because the smaller vessel looked so much like the typical pap boat.
Also pictured below is a more ornate version in celebration of Queen Victoria which I once owned - missing the smaller vessel.
Examples of other shaped, patterned and sized feeding cups: