You will need about £500 ($750) of tools if you buy the real things, but much can be achieved with very much less .......
Computer and microphone, with free recording and FFT software such as “Audacity”, available off the web. Have a look here to see what the options are and how to do it.
A thicknessing gauge that can reach inside the back when it has the sides or bouts on. This is perhaps the tool, along with the small thumb planes that I use most. It cost about £65 ($130) on eBay, new.
There are various plans for making your own from wood etc, but I found that I just couldn’t get the accuracy with a very crude homemade (wooden) version to reach into the back when it has bouts on. But if you only do thicknessing on new plates then simple home - made gauges using levers can work well. Note that training your thumb + first finger (calibrated digits) is also very useful!
A good set of chisels, and/or gauges flat and curved.
A kitchen balance or scales, with better than 1 gram accuracy, shown here with a jap saw.
Thumb planes: they give you blisters after a few hours, but it’s an occupational hazard: wear one leather gardening glove! I have only 2 thumb planes at the moment: one flat bottomed, and one with a convex base for thinning the insides of the plates. It has a 10 mm blade. Martin Smith has been in touch and suggests making thumb planes as shown on dunwellguitar’s web site ( a real neat simple design), and there s detail on how to sharpen scrapers here at ruttan.com’s site. Cheap scraper sheet can be had in UK’s pound shop apparently! Martin wrote
“The harder the metal of the scraper the harder it is to sharpen but the longer it holds the edge. They reckon you need a special burr tool but I use a halfords 3/8 chrome vanadium socket extension bar to round the edge over, it's much harder than the scraper and is easy to hold. I found that the most important part of sharpening is to ensure a smooth square edge on the scraper before rolling the edge over, this really needs the oilstone to get it right. Getting the curl right took me a while but about a 30-40 degree angle from horizontal seems to work well, that and a fair bit of force with a few passes, you really need to be able to feel the burr sticking out. They work better on the maple than the spruce. The thumb planes are a doddle to make, slightly trickier to make blades for, but again the pound shop scrapers came in useful although cutting the blades was hard work with a hacksaw, a dremel would be better. They clog pretty quickly but I'm not precious about them so I've been modifying them as I go along and they work well enough for me (ignorance is bliss).
A small flat plane with about 1 1/4” cut: to tidy up the top of the bouts and blocks. You’ll need a good oil stone to keep it sharp too, and a honing guide to get the angle right: you can make a simple one out of hardwood.
Glue-pot for animal glue: I use a Boots baby-bottle warmer, about $25 new.
It is set at 55 - 68 deg C, a mid-range setting, as I calibrated this one. Do not boil the animal glue, as it is protein-based and is weakened by high temperatures. Add the pearl glue along with water (about 1:2) as it goes into the small pot - the kind used in hotels for marmalade or jam is good for small jobs. When not in use I keep the mini-glue pot in the top of the fridge to stop mould growing on it. Do not use this glue on toast, it tastes disgusting. Note that a violin front needs to be glued on with well diluted glue as it will need to come off again in a few years, and the glue needs to give before the spruce does.
A wax heater such as this Babyliss one can also be used, but I have not checked that this one can go up to 68 deg C.
A ‘Dremel’ type hand-held router. This was a “Power Craft” Combitool sold by Aldi in the UK for less than £25 ($40), with a useful flexible drive shaft. 10k to 35k rpm, but only 160 Watts.
I use this, or its bigger brother to grind down the over-thick bouts (sides) of factory fiddles using a cylindrical sanding head shown.
You can also use this for routing for the purfling with an adapter to keep the distance from the edge and the depth constant , and cutting to a depth of ~1.5 - 2 mm. A Chinese company called ‘music-1982’ sell a ‘dremel and a fixture’ to cut the purfling groove, and a photo of it to be found here.
A drill press. A basic model can be bought new for about £60 ($100), and is indispensable. It may be worth paying more - there are some very useful hints here at Pete Shugg’s Power Tool page about drill-presses. He loves the the Safe-T-Planer cutter too: see later.