Vac kit

Take a sheet of plastic, heat it up, lay it over the solid raised mold, suck it down around the mold with a vacum. You have a sheet with the raised object that you have to cut out of the sheet plastic and attempt to mate it to the other halves without alignment pins. Sound like fun yet! Next thing to scratch building something yourself! Hope you got a better picture of Vacuform kits.

The question was "what is a vac-kit" the answer is a hat full of headaches.
A vac is basicly like form fit packageing that a lot of stuff at the store comes in, if a
regular kit came in a clear package with "bubbles" for each tree picture throwing the
kit away and cutting out the "bubbles" and building them, and scratch building the small
parts out of toothpicks.

What Swanny says ... and don't expect a complete kit of parts that fit together like a conventional injection molded kit. You will probably have to do a lot of reinforcing to get the vac formed parts to hold their shapes, add strips to help them get together along the edges, do a lot of fussing and filling along seams, and if you want an interior you will probably have to bash most of it.
My experience anyway, but sometimes it is the only way to go to get your subject in your scale.
Good luck,
Bruce

Vacuformed polystryene. There are many out there, some good, some bad. Best ones to start with are Koster, MPM, Aerodynamix. Ones to stay away from until you are very competent - ID, Combat. Take a look at my site (link in signiture) look at the Fw-200, it is a vac build. there is also a Russian SB-2 reviewed there which is another vac kit. The PB4Y-1 is a composit of vac and injection. Look the stuff over then email me with any specific questions you may have.