I’ve been playing with Autodesk 123D Make:
It is a great ‘slow prototyper’. It’s lets you make remarkably accurate 3D models out of flat sheet (in this case 2mm boxboard). It is a free download from Autodesk, but also has an online option. You need an *stl or *obj file, you import it into the program and then tell it how construct the model and the programme works out how to cut it out and assemble it. You then download the cut pattern as an *eps (or *pdf) file and either print, cut and assemble the model by hand, or better still import the cut pattern into a laser cutter, then assemble the model by hand.
I wanted to play around with it so I found a good model, the Iron Man helmet (from http://grabcad.com/library/iron-man-helmet) but it was a SolidWorks surface only model, so I spent a bit of time turning it into a SolidWorks solid model (which you can download here: http://www.3dcontentcentral.com/download-model.aspx?catalogid=171&id=366784)
and save it as an *STL file:
The next thing to do is to decide what kind of model you want. 123D Make has a few options. I chose “Stacked Slice” where the model is sliced according to the material dimensions you need. I’m using 2mm boxboard and the laser cutter table dimension is 1200mm x 600mm, but the boxboard available size means the dimension I need is 1050mm x 600mm. Also, the actual tolerance of the boxboard means the width is 2.4mm. Enter these dimensions into 123D Make and the program nests the slices automatically to fit in the sheets. It calculates 3 sheets worth of ‘elevations’, 85 parts in total:
You can change the orientation of the slices, but I’ve found this a little difficult to control, so I left it as the default. To show what happens if you change the material thickness, this is 1mm (it produces 7 sheets, 204 parts):
and at a slice dimension of 10mm, 1 sheet and 20 parts:
There is also construction options for ‘Radial Slices’:
and for ‘Interlocked Slices’, but it depends on what and how you are trying to make:
It is a ‘slow’ prototyper as the construction is by hand and takes a bit of time and does require some care, but 123D Make has some in-built guides which are fantastic. All the parts/ slices are numbered and the program shows the assembly order:
Each part/ slice is numbered, and is marked with guide holes and guide lines for construction:
Most parts have 4 guide pin holes but they are marked North, South, East and West. These can be confusing as only 2 holes line up between slices. For example slice 2 and slice 1 line up North -South, but slice 2 and slice 3 line up East – West.
The next stage is to smooth and fill gaps, then paint. This can take a while, and involves lots of sanding and repeat filling. On a previous model I used a non-water based spakfiller (Selleys ’No More Cracks’ interior timber woodfiller), as a water based filler could cause the boxboard to absorb water and swell:
and then auto-paint grey primer and auto-paint colours, but I found that painting was difficult as even a mild sanding would strip back to the boxboard, and would show through the paint: