Someone just asked how to make a practice phantom since commercially available phantoms are rather expensive and have limited usage life. When training, I use a jello mold filled with objects (mostly dried fruit) for developing scanning and fine needle biopsy skills. It is a homemade phantom that is inexpensive and effective.
2 Large Packages Black Cherry Jello (the darkest color available to disguise the objects you add) + 2 packets of plain Knox gelatin (for firmness)
Disolve Jello and gelatin in 3 cups of hot water (not boiling)
Pour mixture into a 1 quart ziploc freezer bag. Add 12 prunes. Eliminate as much air as possible as you seal the bag. Lay the bag flat in the refrigerator and allow the gelatin to set. It will become quite firm. Remove from the refrigerator, use ultrasound gel, and practice.
Sometimes I add small balloons filled with milk or water for cystocentesis practice.
Many people figured out how to use Jello to make phantoms. I adapted my recipe from Knox Blox. How many of you are old enough to remember those? I think, more recently, they're called Jigglers.