[miniKAT]

Here are my mob spawner designes.

exp grinder: zombies



exp grinder: spiders


The fence bottom lets you hit them while keeping them from crawling through.

mob drowner: skeletons



mob drowner: zombies


You can hit them through the slit too.

[Axel_Hamsen]

Some nice designs, but you can optimize them slightly more. If you add a 2 block drop to the zombiespawner (with the iron bars) they won't be able to be knocked back, and you can keep hitting on them all the time.
And its generally best to always be hitting the mobs from underneath, so there is 0 risk of getting hit by them, unless they are skeletons, in which case I haven't actually tested it...

[dschew888]

Some nice designs, but you can optimize them slightly more. If you add a 2 block drop to the zombiespawner (with the iron bars) they won't be able to be knocked back, and you can keep hitting on them all the time.
And its generally best to always be hitting the mobs from underneath, so there is 0 risk of getting hit by them, unless they are skeletons, in which case I haven't actually tested it...

Skeletons can only hit you if your right under the iron bar if you place a block in front of you they can't hit you.