I use directional freezing with a small, cheap 6-pack Igloo cooler that fits easily in my kitchen freezer. But I quickly got tired of carving ice.

To save time and effort, I picked up a couple cheap silicon ice cube molds that fit snuggly in the top of the cooler. I drilled 5 holes (~1mm each) in the bottom of each cube so that the gasses and minerals could drain through the bottom of the mold as the water freezes. Now I can simply drain the water, remove the molds, break away the excess ice, and pop out perfect cubes without having to do any carving.

It’s a very cheap and effective solution. And I regularly use the cooler as a regular cooler. It makes 12 cubes at a time and takes 16-24 hours to freeze. That’s plenty fast enough for me.

I used to do it by filling a lunchbox cooler with water, letting it freeze, melting off the cloudy ice with hot water, then whacking the resulting slab of clear ice with a rolling pin to get irregular shaped clear iceburgs. Until the cooler cracked.

Now I use a Simply Frozen box, same method really but it makes cubes. And so far (6 years or so) has not cracked.

Directional freezing is the only method that’s worked for me.

Methods that don’t work for me:

Filtering: The dissolved gases don’t get filtered out, and will still form bubbles and cloudiness as it freezes.

Vacuum pressure pulling out dissolved gases: I’ve tried this a dozen times, it just doesn’t get all of it out, even if you bring it to a low pressure boil at room temperature. Or new gas is being dissolved in the time between pulling the ice cube tray out of the vacuum and it freezing a few hours later in the freezer.

I just use those free marketing tumblers they hand out for you to put your coffee in. Or go to a thrift store and buy more for $1 a piece.

Fill it up, put in the freezer, come back in a few hours and pour some water on it if it’s not popping out on its own. Double bag them in the freezer.

If you forget about it it’s fine you just need to break off the bottom not clear part after and check that it didn’t break the tumbler.

You don’t have to worry about them much and they fit basically anywhere and if it breaks it’s cheap enough to replace but is unlikely as it doesn’t expand that much.
Plus the pucks are easier to work with than the big blocks made by using a cooler and take up way less space in the freezer too.
Works well for me and I wouldnt do anything else.

Try Aluminium foil.

Im not into cocktailmaking and stumbled over this in all.

I think either wrapping the whole ice (water) tray in aluminum or having it on the bottom side gives the crystallisation more time to grow without stress so it should grow clear.

Don’t think there form any bubbles

Directional freezing in a dedicated ice cube tray with holes connecting to a water reservoir

There are some products that basically do the same thing as the cooler method, but with a dedicated ice cube tray already cut to size. The idea is that you do the directional freezing in an ice cube tray, and that when the timing is just right, you can pull the whole thing out and just pull the ice cube tray up with formed clear cubes ready to go.

Pros: very easy, nice uniform size and shape with crisp 90° edges.

Cons: gotta get the timing just right, requires buying a dedicated setup for plastic and silicone pieces that aren’t useful for anything else.

Directional freezing in a cooler/ice chest

This is my go-to method, and requires only 2 pieces of equipment in addition to a freezer: a cooler that fits in the freezer, and a serrated knife for cutting cubes. (Note that the serrated knife tends to take a beating, so it doesn’t hurt to have a dedicated cheap knife for this purpose).

1. Take a cooler, take the lid off, fill it halfway with water.
2. Put the lidless cooler in the freezer as an open container.
3. Pull the cooler out 12 hours later or however long for the thickness of the slab of ice to match the size of the ice cubes you want to make.
4. Take the frozen slab of ice off the top and put it on a cutting surface. Discard the excess water.
5. Let the ice warm up to melting temperature throughout the slab, so that the ice doesn’t crack excessively when you cut it.
6. Saw into the ice with a serrated knife, just enough to where you have a distinct line.
7. Hit the ice at the seam, watch the ice split off. If you don’t care about the knife, you can just use the knife as a chisel to hammer at with your palm or even a mallet.
8. Repeat steps 6 and 7 for each cut you want to make, until you have cubes or prisms you want to use. I make 1" x 1" x 5" (2.5 x 2.5 x 12.5 cm) prisms for highball glasses, or 2" (5 cm) cubes for tumblers.
9. Put the ice back in the freezer for later use. I recommend spacing them apart on something until they freeze solid, so that the wet ice doesn’t stick to itself.

Pros: easy, reliable, no special equipment needed.

Cons: the edges and corners tend not to be perfectly straight, if that matters to you. It also tends to take up a lot of space in the freezer while in progress. And if you forget about it, you might find yourself with a big block of ice that you can’t get out of the cooler without thawing.

Other notes: the insulation of the cooler does matter some, as a very well insulated cooler tends to make for a more uniform thickness in the slab of clear ice you make.