The risk that you are taking is that you will end up with 100% of nothing. If you are already in 'struggle on' mode I would re-evaluate the plan to achieve the

The risk that you are taking is that you will end up with 100% of nothing. If you are already in 'struggle on' mode I would re-evaluate the plan to achieve the goal. This comment also assumes that you don't have cash to bring to the table otherwise you would have hired someone already. It really sounds like you need some help so either you need to offer sufficient equity (less than 50% as you have already come a long way although probably more than 20% [over time] unless you are already near launch) to a co-founder OR seek investment which would enable you to hire a contractor. Either way you would need to convince someone of your concept (investor or co-founder) and your personal value to the business. If hardware is required you will need investment at some stage. Kickstarter may also be an option for you if the project is likely to be sufficiently popular but you really need to work out what you are promising first and be prepared to make it public.