You actually won't waste the juice by using a carto, if you do the reverse taryn spin. I use an old knee sock, put a condom part way onto the mouth end of the carto, stick the mouth end down into the bottom of the sock, sometimes I'll tie the sock at the bottom to hold the carto in place, and then spin the sock like a windmill (about 100 times to get the most juice out of the carto). The juice is forced out into the condom and can be poured back into the juice bottle. I've done this with many cartos at once by rubberbanding them together after putting the condoms onto the mouth ends.