The question above is one which is very common among beginning shoemakers, and understandably so given that the glues most often used in industry are generally only available through specialty suppliers. However, there are also options available and accessible for people wanting to make their own shoes at home, and that's what I'd like to talk about here today.
Firstly though, I just need to mention that there are multiple ways of constructing a shoe, and the method used will impact the type of glue used (if any is used at all). This is a huge topic in itself which I won't go into today, but the important thing to know is that the comments here about which glues can be used relate to the method of construction known as cement lasting or cement construction. As the name indicates, this method uses glue (cement) to attach the sole to the shoe upper, and it is the method used in the Atelier Louise shoe patterns.
So let's begin with a glue that you are probably quite familiar with - PVA (common brand names include Aquadhere and Elmer's). It's the white glue that dries clear, and is commonly used for crafts and woodworking, and is often found in schools. When you look at the label on a PVA glue bottle you're likely to see leather and fabric among the list of materials it is suitable for glueing, and this is true - you can use PVA for glueing two pieces of leather together. For example, you could use it to glue the upper and lining straps together on your Silver Sands Sandals. You just need to remember to lightly sand the surfaces you are glueing together so that the glue can adhere properly to the leather (this is necessary regardless of which type of glue you use, otherwise the smooth waxy surface of the leather can prevent the glue from achieving a strong bond). However, this type of glue is NOT strong enough to permanently attach insoles to your straps or shoe upper, or to attach your soles (even when your insoles and/or soles are made from leather). PVA can be found in your local craft or hardware store.
The glue I was trained to use, and which is widely used in industry, is called contact cement (sometimes also called neoprene). It provides a very strong bond so will permanently attach your insoles and soles, and of course you can also use it for your uppers as well if you wish (as I have suggested in the instructions for the Silver Sands Sandals pattern). There are a variety of brands available worldwide, some of the more common ones being Renia Colle de Cologne, Bondura, and Barge Cement. While these tend to be available through specialist suppliers (including some of those listed here), you may also find more readily available alternatives such as Shoe Goo or Selley's Shoe Fix (or similar) at your local shoe repairer or hardware store.
It is extremely important to be aware that contact cements are highly toxic so you must use them in an open, well-ventilated area and you should also wear a mask or respirator designed to protect you from fumes (yes - shoemaking is a glamorous activity!!) If you are pregnant, or think that you might be, I recommend you do NOT use contact cement (if this is the case for you, you may need to think about using PVA for glueing your strap uppers and lining together, and then taking your straps/shoe upper and soling to your local shoe repairer and asking them to attach them for you so that you and your baby are not exposed to the fumes).
Because of its toxicity I was keen to find an alternative to contact cement, and am now using a waterbased adhesive called Renia Aquilim. It's available from Leffler in Australia (product code RNAQU500) or Algeos in the UK (product code RA1167). It is made specifically for bonding materials used in making shoes, prosthetics and orthotics. Having used it exclusively for over a year at the time of writing this, it has been effective for me in providing a strong bond for attaching leather uppers to leather lining, leather straps to leather insoles, and leather insoles to resin soling. It does take a little longer to dry than typical contact cements, but it is definitely worth it to me to not have to be exposed to the toxic fumes of regular contact cements.
The instructions for using the different versions of contact cement can vary. For example, the glues I am most familiar with require the glue to be applied to both surfaces and then left to dry. Then heat is applied (which activates the glue) and the two surfaces are then joined together. Other glues though, instruct you to simply apply the glue and attach the two surfaces. So, the important point here is that you need to read the label of your glue carefully and follow the instructions it gives you when making your shoes.
Well, I hope this has helped to answer some of your questions regarding shoemaking glues, but if you're still unclear about something or you have any other questions regarding shoemaking, then please email me and I'll do my best to help.