Updated 12/31/15, 1/5/16, 1/8/16, 1/27/16, 2/9/16
1. Platinum Preppy Blk F 
Appearance & construction:
2. Platinum Preppy Fountain Pen – 05 Medium Nib – Black
Ordered 1/26/16 from JetPens. Ordered a 2nd 2/9/16.
To convert the Preppy to an eyedropper, see Brian Goulet’s
“Making a Platinum Preppy an Eyedropper Pen” on YouTube. Elizabeth at JetPens says, “The O-ring can be purchased at any hardware store. They should have a 1/16″ thickness, with an outside diameter of 3/8” and inside diameter of 1/4 inch, and are sometimes referred to as #5 O-rings.”
Read “Eyedropper Fountain Pen Pros and Cons,” a warning about possible pitfalls.
The Preppy uses a proprietary ink cartridge so the international cartridges won’t fit.
Update 1/5/16: J. Edmiston: “You are right about the Platinum Preppy. If you want more of these eyedropper pens then just buy the Platinum Preppy 3 pack for about $10 and get some #5 orings and some silicone grease. I carry these around because for a few bucks each I can afford to lose a few” (10/11/10, Amazon customer review). Added: “I got both at the hardware store, plumbing dept. Get the 100% silicone grease.”