Most of the modules in my system were purchased pre-assembled, requiring only a power cable and a couple of screws to mount it to the rack to be up and running, but a couple came as kits that required anything from a couple of hours to a couple of days to assemble.

My most recent kit was a drum module from Synthrotek, the DS-M, a simple but very effective synthesizer that produces a surprisingly wide variety of sounds, from bass drums to crashy cymbals. It arrived in several bags, the front mounting panel and circuit boards, a selection of resistors, capacitors and transistors stuck to a long strip of masking tape, a container of integrated circuits and an instruction manual including a link to an online step by step on their website.

It also included a very cool t-shirt because my order was just over the $99 threshold, and a sticker.

Two nights later and I was adding the module to my rack. I actually wish they'd sent duplicate sets, one for practice and another for the actual build. It wasn't the fault of their online step by step, or their full color sheet of parts showing all the different color coded resistors, but rather my impatience to get it built that was the problem. I somehow soldered the wrong resistor not once but three whole times. Inexcusable I know, but it happened nonetheless. One upside was finding out about solder wick and how it works.

Buying modules in kit form also saves you a lot of money, provided you already have all the tools required for assembly. You'll need a good soldering iron, a soldering iron holder thing with a sponge to clean the tip of excess solder, a tool for snipping the wires after they are soldered to the board, a tool for picking up components that also doubles as a tool for bending one of the resistor wires for vertical placement, some good solder, some solder wick for when you screw up and some kind of magnifying glasses are useful too.

Once you have everything you need to assemble the kits you'll be saving almost half the cost of a pre-assembled unit, which can be quite expensive.

One reason why modules are expensive becomes readily apparent as soon as you start work assembling a kit. It's time consuming work soldering all the components, and the parts themselves are expensive unless you are buying them in the tens of thousands or millions like large production companies do. There's also the cost of designing the circuits, front panel graphics, circuit board production, marketing and anything else you can think of. It all has to be built into the final price.

I've always thought of synthesizer modules as works of art, so the price is always reasonable to my mind, but even without taking that point of view it's actually a relatively inexpensive musical instrument if you take into account all the costs of production.

So whenever possible I would highly recommend purchasing a kit version if available, and to the manufactures I would suggest making kit versions of all your products.