Supplies are the boxed goods town orders ask for, and the board will happily let you accept one you have no way of filling. There are 77 orders in the game.
Sixty eight of them need a building you probably do not have yet. Nine do not, and those nine are only three different items.
So the honest shape of the system is that the order board is a Factory feature wearing a town quest costume, and the early game gives you a very short list.
Three supplies you can make without a Factory
Supply: Iron is the one to aim for. It runs at the 
Woodworking Workbench I or its tier two version, wants six 
Iron Ingot, four 
Board and eight 
Bronze Nails, and the order that asks for it wants exactly one box.
Supply: Fabric is the same bench: four 
Fabric a box, and the order wants five. 
Supply: Clothes I is the 
Sewing Table, twelve Fabric a box, and that order wants twenty, so it is the long one of the three.
One box, at a bench in your Yard you almost certainly already own, from materials you are already making. Nothing else on the board is that close to hand before the Factory exists.
It also pays well for its size. The quest version of that order rewards 20 happiness, where most of the renewable ones pay 10.
Everything else is the Assembly bench or the Kitchen
The 
Assembly bench I makes the hard goods and the 
Kitchen I makes the food and drink, and both live in the Factory. Neither has a version you can put up in the Yard.
The tiers matter as much as the building. Assembly bench I makes three supplies, tier II makes ten and tier III makes fifteen, so the first one you build is not the end of the research.
Supply: Building materials I is one 
Stone Kit and one 
Brick, which is the cheapest recipe on the whole list and reads like something any bench could do.
It runs on the Assembly bench and nowhere else. If you accepted that order early, this is why nothing you build will complete it.
What the Factory costs to reach
Assembly bench I is 
327, 
37 and 
60 of research across ten nodes, then six Reinforced Plank, four Bronze Gear and four Bronze Detail to build.
The research is not the hard part. One of those ten nodes costs no spheres at all and cannot be bought: it opens at 50 reputation with Jack, and the line stops dead until it does.
The food side is separate again. Kitchen I sits on the Farming branch at 225, so a Factory that can box iron still cannot box a vegetable until you have paid a different currency for it.
That hover is worth reading before you accept anything. It is the difference between a board you can work and a board that quietly parks a job you cannot start.
Supply: Iron exists twice, and the two are not the same
Supply: Iron is the one supply with a route on both sides. The Factory version is eight Iron Ingot and nothing else, at Building mastery two.
The Yard version is six Iron Ingot plus four Board and eight Bronze Nails, at Building mastery four. It spends two fewer ingots and pays for them in wood and bronze.
So the bench you use should follow whichever of the two is scarcer at the time. Once the Factory is running, ingots usually are, which makes the older recipe the better one more often than people expect.
Graveyard Keeper 2 Supplies FAQ
Which town orders can you complete without a Factory?
Nine of the 77, covering three items: Supply: Iron at a Woodworking Workbench, Supply: Fabric at the same bench, and Supply: Clothes I at the Sewing Table.
Where is Supply: Building materials I made?
Only on an Assembly bench, at Building mastery 5, from one Stone Kit and one Brick. There is no bench version and no vendor sells it, so the order cannot be filled before the Factory.
What is the easiest town order?
Supply: Iron. The order wants a single box, the bench is in your Yard, and it costs six Iron Ingot, four Board and eight Bronze Nails.
Where are supplies made in Graveyard Keeper 2?
Almost all of them in the Factory: the Assembly bench for hard goods and the Kitchen for food and drink, plus Smithy II for Supply: Steel Tools. Only three have a route outside it.
How many supplies can each Assembly bench tier make?
Three at tier I, ten at tier II and fifteen at tier III, so the first bench is the start of the research rather than the end.
What does the Factory cost to unlock?
327 red, 37 green and 60 blue across ten nodes, plus 50 reputation with Jack on a node that costs no spheres and cannot be bought past.
Why are there so many Supply: Vegetables recipes?
It is one supply that accepts several crops as alternatives, so it lists once per accepted vegetable. Higher quality crops need fewer of them.
Is it bad to accept an order you cannot fill?
The order definitions carry a happiness reward and no penalty field, and the game has no failure or expiry text at all, so it appears to just sit there. That is an absence of evidence rather than a guarantee.
