There are really no exact measurements, since you kinda wing it according to your personal taste preference.
First, cut Spam into 10-12 slices. Next, mix soy sauce and sugar in a small bowl.
Arrange Spam in pan and heat over low to medium heat. After about 1 to 2 minutes, pour the soy sauce/sugar mixture over the Spam.
Keep frying until you reach your desired level of crispness. Once done, transfer the Spam to a plate.
Position the musubi-mold in the middle of the nori. (If you don't have a musubi-mold, you can do what I did and make a ghetto mold by cutting out the closed end of the Spam can... ahahaha)
Scoop some rice into the mold & press down on the rice with the musubi-maker (or spoon). Follow with a slice of Spam, then another layer of rice. Give it one final press to keep this baby together.
Use a spoon (or your musubi handle), press down on the rice and use your other hand to pull the mold up and release the musubi.
Quickly wrap the nori around the rice and let it stand fold side down. The moisture from the rice will "seal" the ends closed. Serve it whole, or slice it in half for easy handling.
I hope you enjoy your Spam Musubi! For more quick, easy, & yummy recipes, please visit me at http://GirlPlusFood.com