I find it best to use a frosting bag to layer the pudding in shot glasses. Make sure to tilt the bag to the side as you fill each glass, as the mixture will be thinner and not hold in the frosting bag as well as a thick frosting would. It will want to escape out of the frosting tip. So, as long as you keep the bag tilted sideways, in between each layer, you should be fine. You can also try using an injector, although some pudding chunks might try and block it.