First a disclaimer- Distilling is illegal to do at home in the US and in many countries worldwide. You need to be a licensed distillery.
That said, there are tens of thousands of people who have stills. If one searches the internet one can find several forums for discussing home distilling, pot stills, artisanal distilling, etc. And one can buys stills of all sizes quite easily. There is federal legislation pending that may allow distilling on residential property, if it passes anyone who passes the steps for the license will be able to distill at home, and sell it legally as well.
As a distiller (my distillery and brewery will open summer 2008) who started out by making infused gin at home I can say that it is both easy to do and difficult to do well. Here's a quick primer on making gin.
Gin can be made in several ways.
Distilled gin, where the botanicals are either dumped in to the still with apx. 30% abv. grain neutral spirits (GNS) or placed in a bucket or on trays that are in the vapor path in the still. Then as the still runs the alcohol vapor pulls essential oils and flavor from the botanicals. Then the distilled gin is brought to 40-45% abv.
Compounded gin, where essential oils are made from assorted botanicals, and these oils are added to GNS that is 40-45% abv.
Infused gin, this is where you take botanicals and infuse them for a short period of time in GNS or vodka, filter, and you have gin. This process will also color the gin anywhere from a light brown, gold, green, etc. based on the botanicals.
Some commercial gins are first distilled and then infused for a short period of time for added flavor and aroma, then filtered clear.
At home the least difficult process is buying essential oils or gin kits and compounding gin.
The second easiest, but much more fun is infusing vodka with botanicals. This is a trial and error process with a steep learning curve. First you need juniper berries. No juniper, no gin. Then whatever other botanicals you fancy. Different botanicals require different amounts of time to infuse. From 12-24 hours for some, down to 30 minutes for others. Green cardomom infuses very fast.So does cinnamon and cassia.
There are around 30 botanicals that can be used to make gin, of which any gin will have 5-20 in the recipe, with most in the 5-8 botanicals range. Off the top of my head some of them are: angelica, anise, licorice, cassia, cinnamon, green cardomom, fennel, orange, lemon, or grapefruit peels, grains of paradise, violet root, iris root, iris flowers, almonds, bitter almonds, cumin, nutmeg, coriander, savory, cubeb, lavender, gentian, etc. Some gins use new botanicals in addition to the standard ones: basil, ginseng, manuka berries, kawakawa leaves, etc.
In addition I have also played with using sumac, allspice, clove, black cardomom, turmeric, celery seed, kala jeera, thyme, rosemary, and a variety of North American herbs that I foraged myself like spicebush, sweet fern, labrador tea, sweetgale, sassafras, sarsparilla, goldenrod, various mints, mugwort, and sages, etc.
According to some definitions, gin is vodka infused with juniper berries, so if you have access to fresh juniper berries, that would seem to be a simple process. According to Wikipedia, however, 'Distilled gin is made by redistilling white grain spirit which has been flavoured with juniper berries' so you'd have to be able to re-distill the alcohol at home.
Would you care to share proportions of botanicals for a basic Gin? I will be using my Grappa setup, which is a reflux still, which can be converted to a pot still, with a perforated basic in the upper third of the liquid area which is used to hold the pomace over boiling water when making grappa.
FYI, if it helps, my favorite gins are boodles and Bombay (not Sapphire).
You are asking one of the most closely guarded secrets there is in distilling. Don't expect a valid answer from anyone who really makes a distilled gin.
I'd go to one of the home distiller forums if I were you. They are more appropriate than here for the questions you are asking. Especially since distilling anything without federal and state permits is illegal in the US. I wouldn't mention your still on this site if I were you.
You can find some recipes out there, but nothing as specific as you want. On page 119 of Bob Emmons book "The book of Gins and Vodkas" there is a simple gin recipe stated for making 1000 gallons.
Sorry, but you have been misinformed. Home distillation and distillation without federal and state permits of alcohol is illegal. You may have been doing it for 20, but it isn't legal. Although research points to figures of over 100,000 home distillers in the US.
TTB FAQ's Page
You cannot produce spirits for beverage purposes without paying taxes and without prior approval of paperwork to operate a distilled spirits plant. [See 26 U.S.C. 5601 & 5602 for some of the criminal penalties.] There are numerous requirements that must be met that make it impractical to produce spirits for personal or beverage use. Some of these requirements are paying special tax, filing an extensive application, filing a bond, providing adequate equipment to measure spirits, providing suitable tanks and pipelines, providing a separate building (other than a dwelling) and maintaining detailed records, and filing reports. All of these requirements are listed in 27 CFR Part 19.
Spirits may be produced for non-beverage purposes for fuel use only without payment of tax, but you also must file an application, receive TTB's approval, and follow requirements, such as construction, use, records and reports.