There are many reasons for replacing the seats in your car, ranging from spills and tears in the current seats, to full-blown race car conversions. Whatever the reason, aftermarket seats can be pricey, and the pre-made brackets that manufacturers sell with them are pricey as well, and that's IF they even make a bracket for your car.
So when I set out to fit some aftermarket seats to my 1989 BMW 325i, I decided to make my own brackets. The level of complexity can vary depending on whether or not you want to add adjustable slider brackets, etc..
My seats didn't have sliders, so I decided to add some aftermarket slider brackets, which upped the complexity, but I'll just go over the basic idea here.
-1/4" x 1-1/4" mild steel bar stock (~5-10' depending on your setup)
-measuring tools (you could get by with just a measuring tape, but something like a caliper comes in handy as well)
-metal working tools (bandsaw, chop saw, angle grinder, drill press, etc)
I built my brackets at the TechShop, in Menlo park, where they have all the tools and equipment I needed, but if all you have is a hacksaw and a cordless drill you could probably do everything but the welding. If you want more info about TechShop, check out their website, www.TechShop.ws
Step 1: Remove your current seat
The first step is to remove your current seats. Typically this is as simple as taking out four bolts and removing the seat. Usually you will not have access to all four bolts without sliding the seat forward and back, and if you have power seats or heated seats, there will be electrical connections underneath that need to be disconnected before the seat can be removed.