I havent tried the sea urchin in photoshop since I don't think it has that tool so it would likely require finding a way to do it by hand or finding a downloadable brush. but the hand drawn comic styled one should be able to be done with the brush or pencil tool (my only uncertainty is how lines look since my cs6 version doesn't have a brush stabilizer versus whatever is available in newer version)
also it's normal if there's gaps in the urchin you'll just have to fill the gaps by hand using the brush tool. watercolor or pen tool should do it depending on size or you can just make the brush larger ^^