No they're not, they're off thingverse, I thought that they'd make a good start of a cruet set - handgrenade for the vinegar and a bomb for a mustard pot!! I'm waiting to upgrade my PC to a higher spec then I'll be able to do CAD
While I'm not sure AutoCAD is the right tool for anything 3D, it should run on fairly low level hardware. What version were you trying to use? You might want to check out Onshape. It's cloud based, so it should run on almost anything that is able to run a WebGL compatible web browser. It's free, but the free version is pretty restrictive if you want to keep your designs private. Autodesk Fusion 360 is another option (free for hobbyists), but is a little more complicated and hardware intensive. There are a few other options out there as well that are free to low cost, but if hardware is a limitation for you, Onshape is what I would recommend to start learning on.
Oh, also, did you pause the print to do two colors of plastic, or did you paint that? Finished product looks great though.
Did you give Onshape a try? It runs through a web browser and most of the computing is done on their servers, so the hardware bar is set extremely low. It isn't perfect by any means and I wouldn't recommend it if you want to use the free version and keep your designs private. That said, it is a great tool to learn parametric modeling. Many of the techniques and ideas carry over to high end engineering and design packages like Solidworks. It's worth giving a try, and there's even an iOS and Android client for it as well if you want to give those a try.