I have printed parts over 80 cm long with my Makerbot 2X (works only with ABS I think). I print them in many little pieces, sand them properly and make a thick mix of ABS and acetone. Then I add the pieces with some Loctite and cover the cracks with the ABS-acetone mix. I let it dry and then sand of the excess plastic and cover a light layer of ABS-acetone mix on the whole model. Then I use acetone vaporing and after that I colour the model. Good and strong solution in my opinion.
A good example of one of the prints (sunglasses for comparison): http://postimg.org/image/hsol7qwrj/ 1
Skip to main content
I think what you are looking for are ‘keys’. Essentially, they allow you to easily reconnect parts after a plane cut or something similar. Bold Machines 1 has a pretty solid tutorial for printing their movie characters, although they dont go over much detail for the software process. Hot glue is apparantly useful also 
I bought the 3D Doodler pen for just this reason, when i have curling at the edge surfaces, I will glue the pieces together and where I have gaps, I will plastic weld the two pieces together to create a smooth surface.
Does this software account for FDM printers hole shrinkage because if I have models that need connector? As a way to combat this issue without an automatic solution I will model the part and offset the hole by .0125" to adjust for printer tolerance.
IF YOU HAVE AUTODESK INVENTOR, LIKE WE DO. THERE IS AN APP TO DOWNLOAD.
OR
CHEERS
BARRY
METACAD ENGINEERING SOLUTIONS LTD
Great to see so many fantastic pieces of software that are making this easier. @MetaCAD do you have any experience of how they cope with thin-walled large builds?
Solvent welding is the best solution I have found. Despite what community trends may lead you to believe, acetone is not ideal for dissolving ABS. MEK (butanone) works far better and is commonly used when assembling plastic model kits. If you don’t have a perfect fit between pieces solvent welding will not produce a strong void-free seam, you need to dissolve some ABS in the solvent to create a glue that can fill the gap. I have also experimented with friction welding (ABS filament in a handheld rotary tool) but I don’t think it’s ideal for most parts as the weld is only on the surface. It has applications, but is more limited than solvent welding.
8 days later
Or you modify your printer a bit…
https://ultimaker.com/en/stories/view/97-printing-out-of-the-box
Thank you @stephan_5 I think this project is really great and shows that innovation can be achieved by questioning, adapting and experimenting with what we already have available.