There have been clear and translucent colors available in PLA for a long time, but no one has offered clear ABS. It’s readily available in sheets, and I wondered why not filament? There is a manufacturer offering it now, somewhere in China. It is currently available from (the unfortunately named) repraper.com in China, www.buy3dink.com/ in the US, and coming soon to http://www.3dprintergear.com.au/. The spool pictured at 3Dprintergear isn’t the same as the other colors, so I don’t know if they are getting it from the same supplier. The same spool style at buy3dink and repraper is also visible at Octave and 3D Printer Supplies at Amazon.
I ordered some clear ABS from Repraper, which cost about $40 including shipping to the US. It took maybe a week to arrive. When I first opened it and looked at the spool, I became a bit concerned.
There are bubbles clearly visible in the filament, and black specs here and there. They look bigger than they are, because the clear plastic magnifies them. This was a fleck of something embedded in the surface about .5mm around. I did a test print of a cup with a wall 1 perimeter thick and .1mm layers.
If you look really close you can see bubbles in the thread, but they don’t stand out too much. They seem to stay contained within the extruded filament rather than bursting and causing a rough extrusion. I figured that a single wall at .1mm layers would give them plenty of opportunity to ruin the print, but they didn’t. The moire pattern you can see on the surface is caused by the extruder motor. Since it rotates in discrete steps rather than continuous motion, there is a slight pulsing to the extrusion, creating that pattern in the clear filament.
The filament varies between 1.55mm and 1.60mm which is a good tolerance, if a little thin. It definitely requires its own Filament profile in Slic3r. I’ve only done a small test, because I’m concerned about the black flecks further down the filament, and worried that one of those could jam my nozzle. I have a roll of white ABS from Octave, who appear to use the same manufacturer judging from the spool. I haven’t seen any sign of bubbles or contamination in that filament, so the trouble might be confined to transparent, or that batch.