This was a guide I wrote a while ago with assistance from @doublenyl on how to attach his rigged Urgarulga Hotdog (futa appendage) to female meshes.

Intermediate level Blender skills are required.

If you are a beginner, do not attempt to do this tutorial until you gather more experience as some details are assumed: knowledge on modelling and basic rigging + weight painting is essential. Work through Crute's beginner list first. Please do your own research when unsure about anything and do not bother the Smutbase blender discord channel unless absolutely necessary.

EDIT: Dreamrider workflow videos included as an example. Also revised to simplify some steps thanks to Dreamrider and crute.

Appending Hotdog Appendage Blender Tutorial – Manual Welding/Bridge Loops, No UV Editing, Shrinkwraps or Booleans

Prerequisites

1. A female (nude) model of your choice.
2. Nyl's Rigged Urgarulga hotdogs
3. Daz importer addon (latest stable version)
4. (Optional, useful to have as reference and comparing your merge) Nyl’s public Wonderwoman or Sindel futa model

Step 0: Prepare hotdog

Nyl's hotdog is too high resolution and without decimating the poly count the merge step will be extremely tedious. Unfortunately the mesh can't be unsubdivided with a multires modifier. One way is to manually dissolve edge loops as Dreamrider has done here:

https://discord.com/channels/202174190558642177/360718065626775555/850870387918766111

Another alternative is to export it into Maya and run mesh reduce.

*Edit: Crute has published a decimated version of Nyl's hotdog here:* https://smutba.se/project/31990/

Step 1: Weld Female Model and Hotdog Model Together

"With my models I completely sew the two meshes together, I don't use any boolean modifiers. I join the meshes and armatures, merge the vertices together, and then clean up the textures and weight paints. It's an involved process.” - Nyl

Simply do as above. In detail:

Merge step:

1. Append the hotdog model to the female model .blend file, or vise versa. Remove all the female character’s clothes which will interfere around the pelvis area.
2. Reset the character and hotdog armature positions in pose mode to origin (alt G/R/S).
3. Position both models within welding distance, resize/rescale the hotdog as necessary, and rotate/move it so it can be easily welded to the female mesh. If welding the hotdog to a model with female genitals, make sure the bottom base of the hotdog doesn’t cover the vaginal area otherwise it will be a nightmare to weld. Edit the base of the hotdog to make it smaller if necessary.
4. You can refer to the Wonderwoman futa model and see how the hotdog is positioned. Note that the Wonderwoman model does not contain any female genitals, and the hotdog in that model drapes all the way to below the anus.
5. Once done positioning, apply rotation/scale/location (ctrl A). Can resize hotdog later as well once everything is done, doesn’t need to be perfect.
6. Rename the UV maps of both models to the same name (Object data properties->UV Maps->Rename), i.e. the hotdog’s UV is called “Model_UV” and this should be changed to whatever the female model’s UV map name is. This will save you an extra step later when texturing since the UV maps will merge automatically. Otherwise you will need to add a UV nodes in the shader editor to specify which UV map to use for which textures.
7. Check bone names of hotdog and female armatures do not collide (otherwise joining will rename duplicates to xxx.001). Rename via bone tab in pose mode. Usually you can skip this step as the bones are unique enough: root, shaft, balls, rod. Though root is used often, so just rename it to NylRoot, etc., to avoid a collision.
8. Join meshes. In object mode: shift select hotdog mesh first, then female mesh. Ctrl J.
9. Join armatures and parent bones. In object mode: shift select hotdog armature, then female armature. Ctrl J.
10. Select joined armature, then go in edit mode: shift select root hotdog bone, then the pelvis bone (or the closest bone the hotdog should follow, sometimes the hip). Ctrl P, keep offset.

At this point you should do some book keeping: go into weight paint mode and check that none of the weights are messed up, and in pose mode check that the character poses normally as before and that the hotdog follows the pelvis/hip as expected.

You may also notice that the shaft hood and hotdog skin forward bones on the hotdog no longer work after merging. These bones previously controlled the shaft forward and foreskin forward shapekeys in the hotdog and need to be relinked. Look up drivers and how to link shapekeys to bones to get these working again.

Welding step:

Before starting the weld, make sure to create a new shapekey as a backup, in case something goes wrong, and also save a copy of the file.

In edit mode:

1. For this step you can either select the hotdog edge loop (at the base) and an edge loop around the female mesh pelvis area and do bridge edge loops (then do some cleanup afterwards), or you can manually merge the vertices together as nyl and dreamrider has done (select a hotdog vertex and then a female mesh vertex, then M->merge at last). This example video from Dreamrider should give you an idea:

https://mega.nz/file/nioxQYxI#sMgl2iyQlLaChmlqjfR4RgqfuDf8j7AgHPVaNgpLOmk

2. Now delete the faces that cover the region of the welded vertices (i.e. create a hole underneath the hotdog base).

3. Now that everything is merged, the weights around the pelvis and hotdog base regions need to be fixed, since we created a hole this step is unavoidable. Weight painting is a large topic so won’t be covered here; in a nutshell, you need to find which bones in the female armature previously influenced the deleted vertices and fix/repaint the areas around the hotdog. Usually the culprits are the hip, pelvis, lower/upper abdomen, upper thigh bones, but every model is different. Check the weights of the Wonderwoman model and try to mimic it as best you can. Roughly the parent bone weights, either the hip or pelvis, should look something like:

4. The pelvis area where the hotdog attaches is a problem region. After done weight painting, check that a thrusting motion with the hip looks fine. Once you’ve done the welding and weight painting steps you’re nearly there; the remainder steps are not nearly as difficult.

Step 2: Sculpting the Hotdog Crus Muscles

At this point your hotdog still won’t look as good as the Wonderwoman model because of anatomy. There are two main muscles surrounding main hotdog shaft (crus of the outer shaft muscle):

These become very prominent when a hotdog is erect. This is modelled into the Wonderwoman model as a shapekey:

You can mimic this appearance in your merged hotdog model, which will greatly add to its realism. The easiest way is to create a shapekey in your futa mesh, and then in the shapekey create the muscle ridge in sculpt mode using a combination of move and add brushes. Since this step can easily be done on your own, will not go into further details, just watch some tutorials on YouTube if you are not familiar with blender sculpting tools and/or shapekeys.

Step 3: Blending the Hotdog and Female Pelvis Textures

“I just use the clone brush in texture paint mode, I don't redo any of the UV's. I'll usually do a pass at full strength, then start smoothing things out by reducing the strength with each pass. Repeat the same process for all textures involved (diffuse, specular, normal, bump, etc.)” - Nyl

1. If you haven’t already, open up an image editing program of your choice, e.g. photoshop and try to match as close as possible the diffuse colour of the hotdog model to the female model. This will provide a good starting point for blending the textures around the seam area.

2. Now switch to texture paint mode (make sure you are in solid viewport shading, as the textures will not update itself in the viewport in material preview and rendered modes) and select the clone stamp tool. Note: from experience it usually looks better cloning from the hotdog textures to the female mesh textures.

3. For diffuse textures you don’t need to do anything extra, you can just start cloning straight away: ctrl-click on the hotdog or pelvis boundaries (depending on the direction of cloning you want to do) to clone that area, then click to apply the clone on the seams. Do a pass at 100%, then repeat at progressively lower clone brush strengths, e.g. 50%, then 25%, 10%, etc. This will help it blend more seamlessly.

4. Now repeat the exact same procedure for all the texture maps, normals, specular, etc. Select the appropriate texture to paint in texture mode (e.g. if I want to paint the normal map, I will just select the normal map texture in the material slot for the hotdog and the torso, then start cloning as before).

5. Make sure to click the Save All Images button once done.

Step 4: Blend the Hotdog and Female Mesh Shaders

Paint a mask texture that blends from the hotdog material to the torso material (white near the seams). This helps hide the specular/shininess difference on the seams even better due to using two different shaders for the torso and hotdog.

Here's an example setup (mixing the torso shader with the hotdog shader, in the hotdog material nodes).

Dreamrider also has a video example here: https://discord.com/channels/202174190558642177/360718065626775555/850856049900388362

Step 5: Render, Animate, and Test

Afterwards that’s it! Start doing some test renders and animations to see if everything works correctly! Usually, you may need to go back to weight painting from time to time or some of the other steps to fix some issues as you find them.

Useful links

• Ciribestgirl: https://twitter.com/ciribestgirl
• Dreamrider: https://twitter.com/Dreamrider3D
• Nyl: https://twitter.com/doublenyl
• Crute: https://twitter.com/therealcrute
• Smutbase discord: https://discord.gg/T2DBVzH