Everyone over at DM Scotty's page http://dmscraft.proboards.com seems to be making magic portals. Here's one by me. :)
I've added a base (but I haven't printed it yet.) I worked within Blender to try and get the tolerances right, so that the gate can be placed inside -- even rotated -- without gluing. I plan to print it soon to try it out.
By request, I've made the gate with a hollow center. I hope it's OK, I had to use a cylinder to cut the middle out using a boolean modifier. I hope I centered it OK. Lesson learned -- don't join stuff together... :)
I used Tsojcanth's awesome Wormy Trampier font - https://tsojcanth.wordpress.com/2016/03/31/new-font-pg-trampier-runes/