I think it's a fine description. Unique, but not so far out there that know sane person would actually think of.
This is one little planet in one tiny solar system in a galaxy that’s barely out of its diapers. I’m old, Dean. Very old. So I invite you to contemplate how insignificant I find you.
It's a little odd, but I think it gets the point across. The only problem would be if it doesn't fit in the context of the story. Just make sure the description fits whoever is describing it (the narrator/viewpoint character). If they normally describe things similarly to this description, then it works perfectly.
Hmm... I'm not so sure. The description is fine upon first glance, but if you stop to think about it, it's a bit confusing.
I'm a little confused as to how such a machine would work though... the mechanics of it, I mean. Part of the reason why a hot glue gun is so useful is because it has the nozzle that allows you to spread the glue in a consistent fashion while pushing the trigger to release to gun at the appropriate rate. However, with a hypodermic needle, you have no need to spread since you're going to inject in the first place. So, why bother?
Unless, of course, what you're doing is you're spreading a very fine line of something and it doesn't actually act as a hypodermic needle. But, in that case I'm not sure why you would describe it like that in the first place.
It might be better to come up with different things that resemble the action of what you're trying to do. Instead of a hot glue gun, for instance, a gun might be a better describer because it has a hint of violence to it as well. Unless, of course, you want to have that consistent flow of fluid that's more apt of the hot glue gun and less like the hypodermic needle. But, then you might want to get rid of the needle imagery, because that usually indicates something going in fast.
I don't know... what's the purpose of this equipment?
Ubi caritas est vera, Deus ibi est.
"The mark of your ignorance is the depth of your belief in injustice and tragedy. What the caterpillar calls the end of the world, the Master calls the butterfly." ~ Richard Bach
