How unhealthy would it be to use a pen cap and then to use the metal part of the pencil for the bowl and to smoke it.
You will regret it gauranteed. Just wait and save up for a pipe or use papers or an apple pipe if you have to.
I can be a glass snob and probably would never do it but, it's not like it is going to kill you. If you're desperate at that is the only way I say go for it. That being said you could always could use an apple, it probably would be easier and faster to make.
Use a pen!!! Not a pencil!!!! Follow this: [ame=http://www.youtube.com/watch?v=tPHmMTCFz0g]Weed pipe with ONLY a pen - YouTube[/ame]