Can you put a bottle of whiskey in the oven

I don't know how hot or how long your polymer clay bakes for, so you might get away with it, but in general I wouldn't risk putting a sealed container in the oven, whatever the contents.

The primary risk isn't alcohol igniting, but vapour forming in the bottle under pressure can break the bottle or more likely the cap. If the alcohol was going to ignite, it would have to get out of the bottle and mix with air anyway. Loosening the lid would relieve the pressure, but there is some chance of hot alcohol fumes igniting if there's an ignition source. This probably wouldn't be catastrophic. The large thermal mass of the contents works in your favour, but the long baking time means the drink can get quite hot.

You may also scorch the label or cap, spoiling the existing print. At the fairly low temperatures used for most polymer clay this isn't too likely,

In general, you wouldn't want to put a sealed glass bottle filled with any liquid in your oven.

If you want to try and are still working on it, remove the cap, empty the alcohol into another container, bake the bottle and cap covered in clay separately leaving room to screw the cap on.

Let the bottle cool completely, then add the alcohol back in.

It's imperative that you let the bottle cool to room temperature, the shock of the oven hot bottle having liquid poured into it would probably shatter it.

In my opinion, baking a sealed, full bottle, is just asking for either a dangerous accident or a big mess.

Use different modelling clay

Two-part putties such as Milliput are just as well designed for fine model-making, and set in air at room temperature.

If you start with a white putty then you can mix it with acrylic paint to colour it. It'll be weaker but this probably isn't an issue. It'll also set faster with the water in the acrylic paint though, so only mix up a small quantity at a time. Or just use plain white and paint it.

It might cause an explosion and a house fire. A sealed bottle would explode without a doubt. The heat differential caused by different thicknesses of clay would stress the glass. The combination of heated alcohol vapour and the heating elements of the oven would probably blow the door off your oven and set your kitchen on fire.

If you decide to go ahead, make sure you video it and leave the room. It would make a spectacular video on social media!

You're making a pressure cooker.

That's a very bad idea. The pressure will escape once it builds high enough. Either will happen:

1. the glass and clay hold together, and the cap blows off, spraying flammable liquid into the hot oven, or
2. the glass and clay shatter, not only spraying flammable liquid into the hot oven but also lots of sharp, high-speed fragments everywhere.

In either case, there will be a fire in the oven, and the glass will probably break.

Bottom line: it's a Bad Idea.

It is a sweet idea for a gift. But heating closed things makes them blow up. Here is how you can get where you want to be safely.

1. Make a sleeve the size of your bottle. Or use an open empty bottle the same size.

2. Decorate sleeve with polymer clay. Or decorate empty bottle with circumferential clay decor.

3. Put decorated sleeve onto gift bottle with a little glue to hold in place. Or slide clay off of empty bottle (if you put it in the freezer bottle will shrink and this should not be hard) and glue pieces onto gift bottle. Curve will be correct.