I would reccommend not making your own, if that's what you mean. They're expensive; you can order non-oem ones through part outlets, or oem ones from your nissan dealership. You can also check on eBay, they pop up occasionally.
Here are some on eBay right now. You'll get them on eBay much, much cheaper than they are new, but there is always a risk that some of them won't work. The following applications will work:
1987 pulsar DOHC coils (CA16DE)
1988-90 pulsar DOHC coils (CA18DE)
CA18DET coils
hope this helps!