Making one product out of several files — a tray and an enclosure — and placing the pieces so they meet.
Some products are not modelled as one thing. A shower is a tray and an enclosure. A washbasin is a basin and a pedestal. A desk is a frame with a top that was drawn in something else entirely. Whoever built them had good reasons — the tray is sold on its own, the pedestal is optional, the top came from a supplier — and none of those reasons help a visitor who wants to look at the finished product.
Combining takes models you have already uploaded and makes one more from them. The result behaves like any other model: one page, one set of options, one embed code, one tap to see it in the room.
Open Models and press Combine. Choose two or more, give the result a name, and press Combine.
The order you choose them in matters. The first model you pick leads: it keeps its own types, and the combined model has exactly the same ones. Pick the shower tray first and your combined product still comes in 900, 1000 and 1200 — the same sizes, under the same names, so anything you have already set up on them still applies.
Everything chosen after that contributes one configuration. If the enclosure comes in three heights, you say which height belongs in this product. Wanting all three is a different product, and for now that means combining three times.
Nothing. Every model you combine has already been converted and paid for, so combining reads what those conversions produced and puts it together. No conversion time is used, and none is used when you re-place a part either.
That is deliberate, because getting two pieces to meet properly is something you do by trying it.
They stay exactly as they were, still work on their own, and still have their own page and their own embeds. A combined model holds its own copy of each piece, which has two consequences worth knowing:
Each model's page lists what it is used in, so you can see what a change would affect before you make it.
By default each piece sits where its author put it. For two Revit families built for the same product that is often already right — a family's origin is a deliberate insertion point, and two families from the same range usually agree about it.
When it is not right, the Made from card on the combined model lets you say how the pieces meet:
Press Rebuild and the model is put together again with the new arrangement.
This is described as a relation, not a position, and that is what makes it survive. "The centre of its bottom meets the centre of the tray's top, 6 mm up" is true of the 900 tray and the 1200 alike — so switching size moves the enclosure with it. A fixed position would be right for whichever size you happened to be looking at and wrong for the rest.
Inside a combined model each piece keeps its own parts, so you can switch off the enclosure's frame without touching the tray's.
Each material within a piece is its own part, even where the piece's author drew several of them as one object.
The exception is hiding by material name rather than by the part row: a material name means what it has always meant — everything in this type made of this material — and in a combined model that reaches across the pieces. The part rows themselves are per piece, so the enclosure's chrome and the tray's chrome are separate rows even when they share a name.
If both pieces contain a material with the same name, VUE renames the second one rather than merging them — you will see something like Chrome (Enclosure) in the material list — because two materials from two different files are not assumed to be the same material.