Stars
Each star bursts in a shape, in its colours, and can fade to others. Crafting one takes a gunpowder and one dye per colour, plus a fire charge for a large ball, a gold nugget for a star, any mob head for the creeper-shaped burst, or a feather for a burst; a small ball needs nothing extra. A diamond adds a trail and glowstone dust a twinkle. All of it must fit one crafting grid, so a star can have up to 8 colours less one for each extra. For fade colours, craft the finished star again with up to 8 dyes.
The rocket
Craft one paper, one to three gunpowder and your stars to make three rockets. The gunpowder sets the flight duration: more flies higher and longer before it bursts. Everything has to fit the grid, so a rocket with one gunpowder takes up to 7 stars and one with three takes up to 5. Every star goes off at once, at the top of the flight.
The give command
Checked against Java Edition 26.3. Since 1.20.5, items carry data components, and a rocket's are written firework_rocket[fireworks={flight_duration:…,explosions:[…]}], with each colour as the game's whole-number colour value (red is 11743532). Paste it into chat with cheats on, or into a command block. The second line is the older form for 1.13 to 1.20.4, which used item NBT ({Fireworks:{Flight:…}}); it fails on newer versions. The colours are the game's firework colours, which are a little different from the dye's own colour.
Rockets for an elytra
Plain rockets with no stars boost an elytra. A rocket burns for about 1.3, 1.8 or 2.3 seconds at flight 1, 2 or 3 (each has a little randomness), and in level flight the boost holds you near 33 blocks a second. So a flight 3 rocket carries you about 76 blocks, and the table divides your trip by that. It counts level flight from rocket to rocket: diving and gliding between rockets stretch it, climbing and take-off use more, so carry spares. A craft of one paper and its gunpowder makes three rockets.
The preview
The burst is drawn with plain coloured dots, not the game's own look, to show the shape, colours, fade, trail and twinkle together. It launches three times and then rests on a still frame; the play button launches it again. If your device asks for reduced motion it shows only the still frame, and the play button runs it once.
Questions
Which flight duration is best for an elytra?
Flight 3 goes furthest per rocket and per craft, but costs three gunpowder a craft. Flight 1 gives the most rockets for your gunpowder and is easier to control. Per gunpowder, flight 1 goes furthest.
What colour values does the command use?
Each dye has a fixed firework colour, written as a decimal number: white 15790320, red 11743532, blue 2437522, and so on. The command lists them in the order you picked them.
Do rockets with stars work for flying?
They boost you the same, but every star explodes on you and hurts. Use plain rockets for an elytra.
Does it work in Bedrock Edition?
The recipes are the same. Bedrock's /give cannot set a firework's stars, so craft them, and its rockets may carry an elytra a slightly different distance.
Does it save anything?
No. The design and trip are kept in the page's address, so Copy link shares exactly what you see. Nothing is stored and nothing is sent anywhere.