This papercraft is an Energy Tank (known as Energy Can in Japan and in Mega Man 7, shortened to E Tank or E Can), first appeared in Mega Man 2, and since then in almost all games from the original Mega Man series, the papercraft is created by Julio Cesar. There are 5 cm and 10 cm two size versions.
It fully recovers the health of the user. The maximum number of E Tanks that could be carried was initially four and was increased to nine for Mega Man 3 to Mega Man 6, but was reduced back to four for the Game Boy games and Mega Man 7. It returned to nine for Mega Man 9 and 10. The E Tank also appears in the Mega Man ZX series, where only one can be carried at a time.
One of the panels in Wily & Right's RockBoard: That's Paradise is an E Tank. In Mega Man: Battle & Chase, they are present in the endings of Mega Man, Proto Man and Guts Man. In the latter, Guts Man buys several E Tanks with the prize money, but he accidentally falls on them. In the game SNK vs. Capcom: Card Fighters DS, the Energy Can is a Counter Card that restores 500 HP.
The E Tank also featured in Mega Man-related media like the Mega Man Megamix manga, the Rockman manga series, the Mega Man comic by Archie Comics, and the Mega Man animated series. In the latter, they are referred to as "Energy Cans", and given to Mega Man by Eddie when his energy is low. They are depicted as cylindrical green objects about the size of a soft drink-can, containing a glowing green liquid that can be drunk to recover lost energy quickly. Eddie can store up to five cans in his head. [Source: wikia]