Justis has said his ProLite cases weigh about 4lbs. A GTF weighs about 2lbs. A Ron Thomas has a similar weight to a GTF.
One thing to consider is that the thickness of the leather is a big part of the weight.
2.5mm leather like we use on the J.Flowers tributes and most of our tooled leather cases will weigh more. 1.5-2 mm leather such as what Justis, Whitten and GTF weighs a lit less.
Here is a chart to show you how thickness corresponds to weight
http://www.brettunsvillage.com/leather/conversions.html
Leather is weighed per square foot - so 8oz leather means that 1 square foot is 8oz. 8oz/3mm leather is typically what you find on saddles for example. A 2x4 case will have about 6 feet of leather used to make it. So a case which uses 8oz leather will have 3lbs of leather on it. A case which uses garment weight leather or 1mm/3oz will have 1lb and 2oz of leather on it. Quite a difference isn't it?
We can do cases in any leather thickness. My current 3x6 weighs just 3lbs in leather. It's made of 1.5mm leather.
We have people who request the thicker leather because they feel that the extra thickness is more durable and solid. Generally the durability is about the same but the case is more solid with thicker leather.
This is felt when the interior tubes and the exterior shell are seperated. Some cases made with thin leather are basically just leather bags which can barely support themselves without the interior shell. Handles and flaps tend to wear out quicker and break easier when done with thinner leather if no precautions are taken to reinforce them.
Murnak does a good job of this. He uses relatively thin leather but his handles and flaps are well attached to the body.
The only other thing to consider with getting a very "light"
tube case is how protective is it really? Most of us case makers cannot afford to use the types of materials which are super strong and super light at the same time. I am talking about carbon fiber, fiberglass, molded aluminum etc... At least I can't.
So what you need to watch out for is when the case maker is using tubes which are flimsy and easy to crush instead of tubes which can withstand acute impact and heavy weight. The assumption by most people when they see a top-loading hard case is that it's tough and will adequately resist these things. Some cases won't and the user should be well aware of the limitations and adjust their behaviour accordingly.
What am I talking about here? Well if you go on a trip for example and you have your $10,000 in cues in a case which will buckle easily if a heavy weight lands on it then you might be in trouble when the baggage handler throws your case on the cart and an 80lb hard shell suitcase lands corner first smack in the middle of your case. Or if you're like one of my customers who was moving a heavy backboard up the basement stairs and watched in horror as it got away from him and bounced down the steps and struck his case squarely in the center driving it into the drywall and making a large dent in the drywall at the top where the case was leaning......you would have been happy to go down the stairs and find that your cues were safe.
I personally will offer the very think flexible tubes on our cases in the future. This will make for a much lighter weight but ultimately less protective case.
I have one now that we call the Tubeless Tube -
http://www.jbcases.com/ordering.html
This one is made just like a regular tube case but - surprise - no tube, has a fabric divided padded interior and with 2mm leather it comes in at 2-2.5lbs. It looks and works like a tube case and protects like a semi-hard butterfly case.
Anyway, that's my little primer on why cases weigh what they do. I have been told that I need to tend to business and spend less time on AZ so adios for now.