Are these the actual stars? Yes. The ilove3d star map draws the roughly 1,600 stars visible to the naked eye — down to magnitude 5 — from the HYG catalogue, and computes each position by sidereal time for the date, hour and coordinates you give it. It is not a decorative texture or a generic sky: shift the date by a month and the constellations rotate exactly as much as they should. The size of each dot reflects the star's real brightness, so Sirius comes out larger than the background stars and the chart reads the way the sky looks. The constellation lines are the standard modern figures, the same ones any planisphere uses. The whole calculation runs in your browser from catalogues bundled into the page, without querying any external service. If you are unsure, generate two dates a few months apart and compare the charts before printing: the difference is obvious at a glance.
Why is East on the left? Because it is a sky chart rather than a map of the ground, and that has been the astronomical convention for centuries. You look at a map of the Earth from above, so East goes on the right. You look at a chart of the sky from below, head tilted up, and in that view East falls on the left: it is the same scene seen from the other side. If the ilove3d star map put East on the right, every constellation would come out mirrored and would not match what you actually see. The practical test is direct: hold the plate above your head with the North edge pointing at true north, look up, and the printed constellations line up one by one with the real ones. It is the same reason a celestial globe shows the constellations mirrored relative to a paper planisphere: you look at one from outside and the other from within.
How do I print it so the stars stand out? With a filament change by layer, which is what separates a readable star map from a plate where nothing stands out. Print the base in dark blue or black, schedule a pause in your slicer at exactly the height where the base ends and the relief begins, then continue in white, silver or gold. The stars, the constellation lines and the text come out in the second colour, and the contrast does all the work. Any modern slicer adds that pause with one click on the layer view. The alternative is printing everything in one colour and painting the relief afterwards with a dry brush dragged across the top, which catches only the raised parts: it looks good, but it takes considerably longer than the pause. If you are printing in a single colour, use a light base and raise the relief height: each star's own shadow then does the contrast work that colour would have done.
What date and time should I set? The one you remember, exactly as you lived it. The ilove3d star map takes your local time and converts it to universal time using the longitude of the place, so you never have to work out time zones or recall whether daylight saving was in force on that date. If the moment you want to mark happened during the day — a birth at three in the afternoon, a wedding at noon — put that hour in anyway, or pick the night of the same date: the stars were exactly there, the sun was just in the way. Changing the hour within the same day rotates the sky around the zenith, so if you want a particular constellation overhead, shifting an hour or two is usually enough to place it. The footer text takes the place and the date, so the moment ends up written on the same piece and needs no separate explanation.
Does it work for the southern hemisphere? Perfectly, and it is not an adaptation: the ilove3d star map calculation is valid at any latitude, pole to pole. From Buenos Aires or Santiago you get the Southern Cross, Canopus and the Magellanic Clouds exactly where they belong that night; from Madrid or New York, the Big Dipper and Polaris. There is no default sky that then gets adjusted: every chart is computed from scratch with the coordinates you entered, so a map of Ushuaia and one of Oslo look nothing alike. And if you enter a latitude near the equator you will see constellations from both hemispheres on the same chart, which is precisely what happens there. Coordinates go in as decimal degrees, the format any online map hands you when you copy a point, with no conversion to degrees and minutes needed. Latitude first, longitude second, negative for south and west.
Where does the data come from? From two open catalogues: HYG, which collects stellar positions and magnitudes under a CC BY-SA licence, and the constellation lines from d3-celestial, under BSD. Both are bundled inside the ilove3d star map page and are never requested from a server at generation time. That decision has a practical consequence beyond privacy: the calculation works offline once the page has loaded, and it does not depend on some external API still existing two years from now. The data is processed into a compact format before bundling, so what gets added to the page is a few hundred kilobytes rather than the several megabytes of the full catalogue. The script that builds that bundle lives in the repository, so the catalogue can be regenerated whenever HYG publishes a new revision. Nothing about the calculation depends on a service staying online.