3D Printing at Helsinki Hacklab
We have one working filament printer, an ultimaker, for details using it see http://kirjoitusalusta.fi/hacklab-ultimaker
There is also another filament printer, a Mendel90 being built but that's not yet usable.
A resin printer is being built, see http://kirjoitusalusta.fi/hacklab-muve3d
Everything else here is general.
Creating models (General stuff)

General:

Solid modelling tools generally produce clean and printable model, mesh modelling tools require extra steps to clean the model

Unless you have some special reason to do it do not bother making voids inside your objects to "conserve plastic" the "slicer" ie the program that converts your STL to GCode (which the printer understands) can manage that automatically according to a fill-ratio you set.

Solid modeling tools:

OpenScad

Programmatic creation of solid shapes. Powerful, but a bit complicated. Works well.

buggy preview rendering (doesn't draw everything correctly)

Use render() call on strategic places or always render whole thing to GCAL (the preview can explode if the CSG tree gets too complex)

Lots of existing code:

github.com/solidcode/MCAD

Thingiverse.com

Forks

github.com/solidcode

ShapeSmith

Parametric solid modelling

WebGL UI, online or local

New, limited features

Freecad

supposed to be better than OpenScad?

not as simple as OpenScad, has more "easy to use" tools etc. (this is either con or pro)

Mesh modellers

Using Google Sketchup to create and print 3D models

Very intuitive user interface

Use the plugin http://www.guitar-list.com/download-software/convert-sketchup-skp-files-dxf-or-stl to export the 3D model to SPL format

Brett's rewrite of skp-to-dxf allows "Right click to export": http://brettbeauregard.com/download/skp_to_Custom.rb rm: http://brettbeauregard.com/blog/2011/06/sketchup-to-stl-plugin-with-no-dialogs/comment-page-1/#comment-19324

use manifold plugin for finding errors from your model http://forums.sketchucation.com/viewtopic.php?f=323&t=25466

there's also stl importer plugin available

if you want to import vector graphics you need to buy pro version or you can download the evalution version of Sketchup 7 pro and then get a free plugin to import dxf format. It's supposed to work even after you lose the pro evalution and the Sketchup converts back to free version. You can probably save the imported vectors to skp and open them with latest version of sketchup.

Blender

hard to learn but otherwise a great tool for 3D printing.

Supports stl export without a any extra plugins

Has a great clay/freeform tool

there's a gcode simulator plugin for ble

hard to learn but otherwise a great tool for 3D printing.

nder at thingiverse, looks good and is probably helping a lot when creating a print.

Alibre

costs some money but should be very good for modeling, it's a pro cad tool after all.

Creating Gcode for printing

http://slic3r.org/

Skeinforge

Cura: http://blog.ultimaker.com/cura-user-manual/

This is the recommended Open Source one for Ultimaker

Printing text

Inkscape

Create text, size: big (150-300ish, type the size to the font size field)

Path -> Object to path

Object -> Ungroup

Extensions -> Modify path -> Flatten beziers (flatness ~0.3-1)

Export as dxf (uncheck both spline checkboxes)

Openscad

linear_extrude(height = 100) import("drawing.dxf");

Save to the same directory a the drawing.dxf

Profit!

Example objects

Ring with decorations - http://kirjoitusalusta.fi/3d-ring-decoration

Fob - http://kirjoitusalusta.fi/3d-fob