Will those who conceive new magazine ideas that do not contradict Islam bear the sin of those who use these ideas in unlawful or un-Islamic ways, and will they be rewarded for those who use them to spread Islamic culture?

The default ruling for things is permissibility. You will be rewarded for inventing this device to propagate the religion and Sharia, and to support the call (to Islam). Whoever alters it and uses it for something forbidden will bear its sin. If we were to prohibit every industry that could be used for something forbidden, then everything would be forbidden, such as weapons and the internet. The default ruling for all of these is permissibility. Whoever uses them for good will be rewarded, and whoever uses them for other than that will bear the sin.