multiple colour sets on alembics, for Maya

This probably contradicts something I've written before, but you CAN export multiple colour sets in Houdini, for alembicking. The key is in the attribute creation. Make sure you use an explicit attribute create node, specify a float, of colour type. Oh and make sure it's on the vertices, because Maya. It will now show up along trusty ol' Cd in Maya's Color Set Manager.

alternative to copy stamping

Copy Stamping is a bit slow, here's another way of copying things using point attributes.
EG - a bunch of points comprising of cubes, spheres and donuts.

1. get a bunch of points!
2. give them an id attribute eg 1,2,3,4..which will represent cube,sphere,donut. The attribute randomise node is quite good for this. There is a setting called Discrete Values which you can tweak with weighting. Eg. 20% value 1, 40%value 2, 40% value 3. Lets call the attribute ID
3. Create a For-Each-Loop network. Set the mode to "points". By default it is set to process "pieces". Uncheck the use "name" bit. This is to do with the fracturing rigid body workflow.
4. Connect the cube, sphere and donut to a switch node. In the index box type: point("../foreach1/",0,"ID",0)    this references the current point being processed by the foreach loop and reads it's corresponding ID value.
5. Inside the foreach loop add a "copy to points" node. Connect the switch node to this.
6. This should all work now!