i was wondering if there was any special procedure to this ..not just make a huge map

Always thought it's just a question of scale, isn't it?

Usefull topic
And lot's of work

I think that walls are func_illusionary and there are clip and invisible textures on walls where the invisible texture is set on 255 in reliably panel . Sry for my bad english.

Why "usefull"?

It's not as easy as it can seems...

Milburn, you can hurt s3b hard..he like that...

Rhoooo

Au lieu de faire le con tu ferais mieux de nous répondre

to make a rats map, assemble your room on the miniature level. once you are happy with the results use the transform->scale to multiply your room to your liking. Multiplying by 6-8 is pretty reasonable, as units of 16 would become units of 96/128, a sizable amount for players to walk through a hallway that could basically be a drawer or part of a bookshelf. EDIT: of course, you may even want to go larger than this! the original rats map used basic half-life prefabs, so it was considerably easy making the layout. adjust the textures to the scale you just multiplied. you can also save your room as a prefab, and reapply your room as a prefab with larger dimensions if adjusting the textures is too time consuming for you. Once your room is finished and resized, make the tunnels and ledges that you seem fit. using brushes that are clipped, received vertex manipulation, or are angled may cause problems with this method.

back in the old days there was a tut for rats map. but of course, all the old days sites are dead, and theres little possibility of me reviving the old tuts. but thats just some of the ways that could ease your process of making the map.