I like the homemade ones best. I use what I have on hand usually chunky peanut butter. and lard or shortning and either molasses or corn syrup, soften in the microwave till soft a minute or two. add nuts or seeds or berrys or old cereal or dry bread crumbs and thicken with cornmeal or wheat flour or mixed bird seed till I have a thick dough. I either press it all into a flat pan or in the trays the commercal ones come in or the halfs of plastic boxes that raspberrys or blackberrys come in. toss them in the freezer till I need them. the flat pan ones I cut into squares or chunks and the other I pop out of the trays and put in the wire cages as far as the seed blocks I use either gelatan or corn syrup and bird seed mixes and mold them into bars or in bowls or pans and freeze them till they stiffen.

Thanks dklucius- you response is exactly the kind of response I was hoping for.

I hadn't thought of using molasses- will have to try that. Hadn't thought of using the trays the commercial cakes come in either- I've been using a regular tray and just trying to cut them close to size to fit into the cages, always with trim scrap. I'll have to save up a few of those commercial containers, sounds like that would make the sizes easier to make right and less scrap.

I use lard. I melt about 4 cups of lard, shut off stove, add two cups of chunky peanut butter and stir until that is melted. Then I add 1/3 cup of sugar, 2 cups finely ground sunflower kernels, two cups of white flour and enough corn meal to get the texture you like. I think I end up with around 3 to 4 cups of the cornmeal. I put it in a square pan, let cool and cut into four pieces, which fit perfectly in the suet cage. I also keep some in a container for crumbling into a bowl. Once I started making these the birds ignored the commercial suet. They definitely preferred the homemade suet.

I'm curious as to why you're adding sugar/corn syrup/molasses to what is essentially a home made suet cake regardless of what product you use to take the place of real beef suet. I would assume that the only natural "sweet" wild birds might encounter would probably be in fruits and/or berries of one kind or another... therefore the question. On the other hand, if you're using the sweeteners as "glue" to hold a seed ball together, it possibly makes more sense...
As to the "glue" that holds commercially available seed blocks together, its typically gelatin (think of old time school glue with the rubber top that you'd bend over to dispense the glue) although I've always assumed that a flour or corn starch paste would also work if you could figure out the correct consistency and have some way to dry out the block.
I started making my own suet cakes last year since our back yard birds won't touch the commercial types. Note that I only use it during cold weather (in addition to two seed type feeders) and the birds scarf it right down. Recipe is simple and absolute amounts of this or that might vary up or down depending on what I have on hand...
*I ea. small block of lard (one lb. size). Bacon fat might work I in a pinch but would contain salt and chemical residues from the curing process.
*1 ea. small jar of chunky peanut butter
*Sizable portion of cornmeal (the more coarse the better)
*Heaping handful or so of rolled oats (acts as a binder) although steel cut oats work almost as well
*Big handful or more of raw peanuts whizzed through the food processor just enough to break into smaller bits. You can also do this by smacking the peanuts between a hard surface (the anvil) and the bottom of a heavy pan (the hammer) but it's a lot messier since the broken bits tend to scatter everywhere..
*Handful of black oil sunflower seeds
*Handful of plain birdseed
*About a half handful of raisins
And some amount of shelled sunflower kernels (salt free), safflower kernels, or other natural bird goodies as you see fit and might have on hand.
Melt all together over medium to low heat and add more oats as necessary to obtain the desired consistency. I use a metal cake pan to pour the goop into until nearly cool, cut into the size required, wrap in tinfoil or plastic wrap and then store in the frig until needed.
Steve

when its hot the lard and shortning and grease recipes tend to melt but the sorgum and molasses and corn syrup don't melt as bad. the birds get lots of energy from the lard and shortning from the fats but they also get lots of energy from the sweet ones too. spring and summer I get lots of orioles and tanagers and grosbeaks that like he sweet suet but also love jam and jelly and fruits also.