By "bad designs" I will assume you are referring to the existence of death and pain. This is only a problem from a non-eternal worldview. Below is one worldview in which this is not a problem.
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1. God is eternal
2. Evil is temporary
3. Without wounds there can be no healing
Without wrong doing there can be no forgiveness
Without death there can be no resurrection
Without sacrifice there can be no love
God in himself is loving and merciful and all that good stuff.. but in order to play out these attributes so that WE can know him - evil must temporarily exist.
Imperfection is an infinitesimally small blip in eternity that God endures only because it is essential to reveal Gods glory, which lasts forever.
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The above stated worldview is one based off of an interpretation of Romans 9:22-23 in the bible.
"Rom 9:22 [What] if God, willing to shew [his] wrath, and to make
his power known, endured with much longsuffering the vessels of
wrath fitted to destruction:
Rom 9:23 And that he might make known the riches of his glory on
the vessels of mercy, which he had afore prepared unto glory."