Ok i made a hollow cylinder and all, but some reason it appears that my cylinder doesn't have a roof or a floor? Does anyone know how to fix this prob?

Thanx

You need to use the 'CAP' facility from the CYLINDER menu.

Select the brush then select the cap option from the menu and voila! All done!

You need to put "caps" on your cylinder. It's kind of like putting a lid on a can. On the toolbar (if you're using JK2Radiant) the button that is 4th from the right should do it, or just go to the "curves" drop down menu and select "caps". And of course make sure you've selected your cylinder first. You can put caps on any patch mesh. Both ends of the cylinder will be capped, if you only want to cap one end, you need to ungroup it after the caps have been put on and then individually select the cap you don't want and delete it.

Hope this helps.:)

I already tryed that, and it didnt seem to do anything!

You have to invert both capped ends. Select the cylinder and shift select the main part of it so that both caps are now selected. Go to curve > matrix > invert

I think you might have to ungroup your cylinder if it doesn't allow you to deselect the main middle portion. Right click on it and click ungroup entities.

If you have something func_grouped, such as a capped cyclinder, you should be able to cycle through the individual pieces using the TAB key.