From the photos you can see I use cole jaws to glue rings, after rings are dry then I will flaten them and stack. I do have pipe and bar clamps also to use in assembly.
Glue slip is less of a problem for me using the funnels. I can see my alignment better. I use a sink cutout to glue wedges by hand or hose clamps, you can see that on top of the portable table saw.