I've been bonding my ABS models together using Acetone for a couple of years now, and although this works well there are a few things I don't like about it. Firstly Acetone is really low in viscosity so it tends to capillary along the fine thread like structure of an FDM model. Sometimes you want this and sometimes you don't. It can spoil the surface finish of an otherwise pure printed surface. Also it can more easily get onto your hands and contaminate additional surfaces, so you have to be ultra careful. Another reason I don't like acetone for bonding is you need to apply it several times to both faces to soften the plastic enough to create the bond, which takes time and increases the risk of getting it where you don't want it. I also find that it only creates a really good bond if there is a reasonable compressive contact between all of the faces to be bonded. I.e. no gap filling. Lastly, it evaporates really quickly, so bonding large areas is more difficult because one part of the model has already dried before you've finished applying it to the other side. So if you don't use Acetone, what's the answer?
Well, I'm refurb'ing my bathroom at the moment and came across the solvent plumbers use for bonding plastic waste pipe. It's specifically designed for bonding ABS (and uPVC). It works a treat. It smells like acetone but it's much more viscous. It's completely clear, it stays where you put it and doesn't capillary, you only need to apply it to one of the 2 bonding faces, it gap fills nicely (small gaps I'm guessing only as it works with mine), and you only need to apply it once because it doesn't evaporate anything like as quickly as acetone, which makes bonding large areas easy. Having discovered this I don't think I'll use acetone anymore for bonding. I've only tried it on same coloured parts and don't know what bonding 2 different colours would do with regards to colour leeching but I don't suppose it will be an issue. On the parts I've bonded the quality and control this gives you is outstanding compared with acetone.
Anyway, thought I'd share.