Step 1:
To start off, create a new document 500x500px with a white background.

Step 2:
Select a soft rounded brush with a diameter of 45px. Set both the opacity and the flow to 35%.

Step 3:
Next, set the foreground colour to #660000.

Step 4:
Using the brush tool scribble on your white canvas until it looks like something in the picture below.

Step 5:
Set the foreground colour to #990000 and scribble some more onto your canvas.

Step 6:
Set your foreground colour to #CC0000 and keep on scribbling on the canvas. You should now have something that looks like this.

Step 7:
Now select ‘Filter’ then ‘Artistic’ and then ‘Plastic wrap’.

Step 8:
Set the ‘Highlight Strength’ to 5, and ‘Detail’ to 15 and ‘Smoothness’ to 5.

Step 9:
After you have applied them settings, click on ‘Image’ then ‘Adjustments’ then ‘Brightness/Contrast’ and set the ‘Brightness’ to -25 and the ‘Contrast’ to +40.

Step 10:
If you have followed all the steps in this tutorial correctly you should have something that looks like this.

Another variation can be found below.

Step 11:
I hope that you enjoyed learning how to make guts in Photoshop and will try different methods to create different variations.

Good Luck and remember to experiment! Tutorial originally written by shrood. Permission given to display the tutorial.