A cavity is not a pocket.
It has to let go of the part
Nothing draws out of a straight-sided cavity: the sheet shrinks onto the walls as it cools and tears coming off. So a forming tool is a block with drafted cavities in it, a radius where each floor meets its wall, and a vent through every one — and it is laid out in rows about the centre line the machine has. This builds that and writes the STL. Free, in full. No sign-up.
- Free, no account.
- Every feature, every machine set and every file is free from the first open — no seat, no licence, no watermark.
- Nothing is uploaded.
- The solid is built in your browser and the STL is written there. No drawing of yours goes anywhere.
- Millimetres, from the centre.
- Every figure is a real size measured from the plate's centre, so growing the blank moves no hole.
- Machine sets you own.
- The mounting patterns are a JSON file. Add your machines to it and they are in the panel.
- Weight before you send it.
- Volume and mass off the closed solid, in the stock you picked — the figure the payload is judged on.
- STL that lands right.
- Binary, millimetres, Z up and standing on zero. Nothing to rotate at the other end.
What it does
Six things, and the first is the one the tool lives by
A forming tool is not a complicated object. It is a few operations that all have to be right.
Draft, floor and vent
- Walls that lean out, so the part lifts
- A radius where the floor meets the wall
- A vent through every floor, or it will not pull
- Warned about, loudly, when any is missing
The cavity grid
- A mould is a grid, hardly ever one cavity
- Pitch across and along, centre to centre
- The grid stays centred on the tool
- Adding a row does not move it off the machine
A block of stock
- Width, depth and thickness in millimetres
- Rounded outline corners if you want them
- Six stocks, aluminium to printed PETG
- Its centre is the origin for everything else
Everything else a tool needs
- Bolt holes, water channels, register pads
- Pockets and windows, turned to any angle
- Added as well as cut — bosses and ribs
- Through, or blind from either face
What it can do
Everything the panel holds
The whole of it, so nothing has to be found by accident.
The cavity
- Draft in degrees, on every wall
- A radius where the floor meets the wall
- A vent through the floor, in tenths of a millimetre
- Rounded corners in plan, turned to any angle
- Depth from the top face, in millimetres
The grid and the block
- Rows, columns and a pitch each way
- The grid stays centred on the tool whatever the count
- Block width, depth and thickness, 5 mm to 3 m
- Six stocks with real densities, aluminium to PETG
- Two holes on a line, four on a rectangle — each one feature
The machine
- Bolt circles and rectangular patterns
- A centring spigot as a counterbore in the mounting face
- The plate thickness that machine is usually tooled at
- Six sets to start with, in an editable JSON file
- A four-hole circle arrives as one corner feature
Out
- Binary STL in millimetres, Z up, on zero
- Volume and mass off the closed shell
- Triangle count and how many booleans it took
- A warning when a shell comes back inside out
- Nothing is uploaded: it is all built in your browser
How it works
Four steps
Set the block
Width, depth, thickness and the stock. Its centre becomes the origin for everything after.
Sink a cavity
Size, depth, draft, floor radius and vent — then rows, columns and the pitch.
Add the fixings
Bolt patterns, channels and pads. A machine set drops its fixing on at the centre.
Take the STL
Millimetres, Z up, standing on zero. The panel says what it weighs first.
What it is for
Where a plate is wanted by Friday
Blisters and trays
A cavity grid for a thermoformer, at the pitch the machine indexes and centred on its own line.
Change parts
A new pack size means a new tool. The old one is a few figures away, and the grid recentres itself.
Drinks and dairy
Pick plates for cans and bottles: a grid of holes on one rectangle, moved as one thing.
Labelling and coding
Backers and mounting brackets that have to clear a print head by a known amount.
Guards and guides
Wear strips and dead plates in POM or nylon, where the weight matters as much as the shape.
Printed first fits
The same file in PETG at a third of the weight, to try on the machine before it is cut.
Questions
The ones worth answering
Is this CAD?
No, and it does not pretend to be. It builds one kind of object — a block with drafted cavities and holes in it — because that is what a forming tool is, and it does it without a seat, a licence or a fortnight of learning. Anything with a shaped product form in it wants a real modeller.
Why does every cavity need draft?
Because the sheet shrinks onto the walls as it cools. With vertical walls it grips, and the part tears or stays in the tool. Two to five degrees is the usual range for a thermoformed pack and more for a deep draw; the panel warns when there is none, because it is the one mistake that makes the whole block scrap.
Mould or mold?
The same thing. This site is written in British spelling throughout — colour, millimetres, centre — so the service is Moulder and the address is /mould. If you searched for a mold generator you are in the right place.
Why is everything measured from the centre?
Because a machine's spigot is on the centre line and the part it handles is centred on it. Measure from a corner and every figure changes the moment the blank does, which is exactly how a plate comes back from the mill with all of it ten millimetres out.
What units is the STL in?
Millimetres. STL has no unit and never has, and every reader assumes whatever it assumes — the overwhelming convention in this trade is one unit to the millimetre, so that is what is written, with Z up and the part standing on zero. It lands on a bed or a printer plate the right way up with nothing to rotate.
Can I add my own machines?
Yes, and that is what the file is for. The sets live in a JSON file the tool reads at run time. Add yours to it and they appear in the panel next to the others. The ones shipped are a starting point: the bolt circle and the hole count come straight out of the ISO designation and can be trusted, the spigot and the thickness are sensible figures and must be checked against your machine's drawing.
How accurate is a hole?
A hole is drawn with 64 segments, which puts a 12 mm hole under a hundredth of a millimetre off across the flats. That is a mesh format's limit, not a fit: a dowel hole is still reamed to size and the STL is what tells the shop where it goes.
Why does it say the shell is inside out?
Because the volume of a closed mesh comes back negative when it is, and a file like that prints as a hollow shell or fails to slice at all. It should never happen; if it does, moving the feature that caused it by a tenth of a millimetre nearly always clears it — two surfaces exactly touching is the one case boolean geometry does badly.
Build the tool the machine actually runs
Set the block, sink the cavities, add the fixings, and take the STL.