oshi sushi

One of the easiest types of sushi you can make is oshi sushi. Oshi sushi resembles nigri sushi in some ways, but it's not made by hand per se. When making Oshi sushi, a press is required. The press I use is a small plastic one that cost me a few dollars at an Asian food store.
Here's the oshi sushi box with nothing in it. There's a lid and base piece that aren't visible here. You simple put one of the pieces on the bottom to begin.
Start by filling the box about 2/3 of the way up with sushi rice.
In order to best gauge how large to cut your toppings, you may want to place the lid on top of whatever you're cutting (if cutting is necessary for the chosen topping).
Lay your topping or toppings on top of the rice. Here I have some baked sweet potato slices.
Here's some sushi omelet going on top of the sweet potato. You may also have a layer of nori, or rice in between layers of topping.
Place the lid on the top, and using even pressure, press the sushi.
Take the lid off the top, lift the box, and place the lid on the bottom to elevate the oshi sushi a bit so your knife cuts cleanly through each layer to the bottom.
Slice your oshi-sushi with a sharp knife inside each of the slits on the box.
Here's the finished sushi. It's uniform and interesting, and easier to make than most other types.
Here's a cut piece of mackerel sushi. Notice how uniform the shape and size is.
And finally, here's the mackerel sushi presented. There's less artistry involved, but it's quick, easy, and still looks great.