Portal Design And Detail
The most important thing in any map is design and detail. This is especially important when making a portal map. A portal map needs to have a good layout, be fun to play, and be visually attractive.
The first step to use when making a Portal map is to first design a rough, and simple map. This is generally done with dev textures, and it is generally completed in about 4-5 minutes. At this point, you should thoroughly play test this area, and determine what areas will be portable and non portable.
Now detail the areas where portals will be placed. I moved the top section in and added a hazard texture, and I shrunk the floor and made it into a platform.
Now add metal textures where players will not be able to place portals on. The metal textures will have standard detail for now. Play test this section again, and find any glitches.
Now add doors, buttons, catchers, and triggers for the area. Now play test the section thoroughly. It will be very difficult to modify the detailed walls afterwards.
Now, add detail in the metal areas. See Detailing metal walls for more information.
Now, finish off the rest of the section.
Next add lights. The trick is to have them uneven. That way it is more attractive. The best white texture to use is white001. If your hole is 64x64 or larger, place an invisible-textured block in it to prevent the player or boxes from getting into it.
Admire a job well done and fix minor texture alignments and bugs.