Can You Make MICR Ink?
If you tried to make a MICR Inkjet cartridge, all the magnetic particles would simply settle to the bottom, and you'd be left with regular ink. So the right kind of ink simply is not available. ... It is even possible to buy MICR toner cartridges specifically for check printing.
The MICR line on checks must be printed using magnetic toner. This special toner is only available for laser printers (and some special dot matrix printers.) Inkjet printers can not print MICR! In general, your printer manufacturer will not sell this special toner.
What do you need to print MICR?
Can you make your own magnetic ink?
Here [Catarina Mota] is showing off a ring of magnetic ink printed on a piece of paper. By mixing it with acrylic medium in a vortex mixer you end up with a homogeneous ink. ... There's a quick demo after the break that shows how well this printed ring holds the magnet.
Make Your Own Magnetic Ink | Hackaday
MICR characters are printed on documents in one of the two MICR fonts, using magnetizable (commonly known as magnetic) ink or toner, usually containing iron oxide.
Magnetic ink character recognition - Wikipedia