1. You could buy sushi vinegar from the supermarket or Asian grocery store instead of making it from scratch. For the required quantity of store-bought sushi vinegar, refer to the instructions on the bottle.
2. You need to use sushi rice, short grain rice or medium grain rice (order of preference). Please refer to How to Cook Rice the Japanese Way but add 2 sheets of 10cm x 10cm (4" x 4") konbu (kelp) when cooking the rice if you can. This will add umami to the rice.
3. The quantity of ingredients is approximate as it all depends on how much people can eat and how much rice vs ingredients people use to make temakizushi.
4. If you prefer, you can spread a small amount of wasabi onto the sashimi before rolling. Alternatively, dissolve wasabi in the dipping soy auce.
5. I did not include flavoured grilled eel, tuna belly and hikiwari nattō (finely chopped fermented soya beans) which are also in the photo because they are not commonly consumed. But if you are interested, you could buy a frozen version of these at Japanese grocery stores. Hikiwari nattō will need to be mixed with finely chopped shallots (scallions).
Pickles are also excluded as they might not be be readily available in your country. But if you happen to have it, by all means, cut them like the cucumber.