If it is interesting for you to see how my completely 3d printed 2-cavity injection molds without aluminium frame performed you can see the results.
Additonally I will show you how to design the molds with some references under https://plasticlabs.wordpress.com/2016/09/06/how-to-bring-a-3d-printed-2-cavity-injection-mold-to-life-part-1/
Second part will be ready next week - 13th september 2016