Build Your Custom Serum
Please do your own research on ingredients, your skin type, and how to achieve your skincare goals. This is for experienced skincare users only.
Create your own custom facial oil or serum by selecting your preferred base oils, functional ingredients, and optional add-ons. Every choice changes the texture, absorption, and overall performance of your final product, so take your time and build something that feels right for your skin.
At Cosmocost, customization is meant to be real. You are not being pushed into a small group of pre-made products through a quiz. You are choosing the ingredients you want, the strengths you prefer, and building something that actually fits your skincare goals.
Formulation Guide
Step 1: Choose Your Base Oils
Your base oils create the foundation of your formula and have the biggest effect on how your serum feels on the skin.
You can use one base oil or blend multiple base oils to create your preferred balance of richness, absorption, and skin feel.
Step 2: Choose Functional Ingredients
Next, add your actives based on your skincare goals. These are performance-driven ingredients such as vitamin C derivatives, peptides, antioxidants, retinoids, and botanical extracts.
Each ingredient adds its own benefits and can also change the feel of your final formula. Some ingredients are best for brightening, others for hydration, smoothing, antioxidant support, or improving the look of firmness and texture.
Step 3: Customize Strengths
Some ingredients allow you to choose your preferred strength. This gives you more control over the performance and feel of your formula.
For example, you may begin with a lower percentage of THDA or retinol and gradually increase over time while keeping the rest of your formula the same. This makes it easier to fine-tune your skincare as your skin changes or as your comfort level grows.
Higher percentages can increase potency and may also slightly change the texture or richness of the final product.
Step 4: Add Optional Finishing Touches
You can customize your formula further with optional oil additives, scent choices, bottle upgrades, and label options.
These finishing touches can affect the feel, scent, appearance, and packaging performance of your final product.
General Tips:
Store your serum in a cool, dark place unless otherwise noted for a specific ingredient.
Shake gently before each use if needed to help keep the blend uniform.
If you are new to active ingredients, start simple. One or two actives is often the best starting point.
Even natural ingredients can affect the color, scent, and texture of the final
Smart Compatibility Logic:
Our custom builder automatically prevents incompatible ingredients from being selected together. Certain ingredients can affect the stability or performance of others, especially when liposomes, peptides, or penetration-enhancing solvents are involved.
If an ingredient is not compatible with another one you have selected, it may be hidden automatically in the builder. This helps create formulas that are more stable, effective, and thoughtfully designed without requiring you to figure out complex formulation rules on your own.